billguard is a personal finance security and productivity company .

its mobile and website application scans credit card and debit card transactions , alerting users to possible scams , billing errors , fraudulent charges and hidden fees .

as of october 2014 , billguard reports it has flagged over $ 60 million of suspect charges on behalf of its users , drawing from over $ 1 billion of monitored transactions .

in september 2015 , billguard was acquired by prosper marketplace .

billguard was named " one of the top online banking innovations of all time " by marketconsensus .

and a “ top 10 tech company ” by american banker .

billguard is also ranked as the " top 2015 most powerful financial protection app " by advisoryhq news .

billguard

billguard <EOT> billguard on abc news 7 in san franciscoget the billguard app : android - urltoken ipho . . .

billguard vs . mint : mint is not a financial protection app . billguard ( prosper daily ) is .

billguard on cnbc ' s power pitchget the billguard app : android - urltoken iphone - http . . .

billguard on the today showjanuary 8 , 2015 get the billguard app : android - urltoken i . . .

in his first visit to israel after buying billguard , prosper ceo aaron vermut says billguard staff wi . . .

mint vs . billguard : mint is not designed to be an id protection app . billguard ( prosper daily ) is .

billguard ' s founder , raphael ouzan , currently has an approval rating of 61 % . billguard ' s primary competitors are

mint vs . billguard : billguard ( prosper daily ) is a personal finance security company , while mint is a personal finance company .

to satisfy some of these questions about the billguard app , particularly when considering billguard vs . mint , we began by reviewing as much informational content as we could find on billguard ( prosper daily ) .

mint vs . billguard : mint is designed to be an all - inclusive personal finance app . billguard ( prosper daily ) is not .

billguard - billguard was a personal finance analytics app that empowered consumers to control , protect and do more with their money . | startup ranking

owler has collected 15 screenshots of billguard ' s website since oct 2012 . the latest billguard website design screenshot was captured in aug 2017 .

despite the high levels of security that billguard reviews applaud the billguard app for , there is no personal finance software that is 100 % safe .

a billguard review in forbes magazine reports that , in four years , billguard ' s expense tracking software helped identify over $ 70 million in unauthorized charges .

billguard vs . mint : mint is not designed to alert you whenever there are suspicious activities on your credit card . billguard ( prosper daily ) is .

billguard currently has 32 followers on twitter . as of july 2013 billguard had 2 , 198 followers . that ' s a 98 percent decrease in 4 years

since billguard was founded in 2009 , it has participated in 3 rounds of funding . in total billguard has raised $ 16 . 9m . billguard ' s last funding round was on sep 2014 for a total of $ 3 . 9m

billguard currently has 4 , 908 fans on facebook . as of july 2013 billguard had 1 , 934 fans . that ' s a 153 percent increase in 1year

billguard is a personal finance security platform that enables users to track and monitor their spending across credit and debit card transactions . billguard ' s headquarters is in san francisco , california . raphael ouzan is the founder of billguard . billguard ' s latest funding round was a crowdfunding for $ 3 . 9m on sep 2014 . billguard ' s main competitors are mint software , personal capital and credit karma . as of december 2014 , billguard has 4 . 9k fans on facebook and 32 followers on twitter .

help ! i can ' t add my account . billguard faq & support center : http : / / help . billguard . com . get the billg . . .

credit karma is billguard ' s # 3 rival . credit karma is headquartered in san francisco , california , and was founded in 2007 . like billguard , credit karma also competes in the internet software industry . credit karma generates 228 % the revenue of billguard .

billguard started as a piece of financial planning software to offer expense tracking and credit monitoring services . in 2015 , billguard announced that it would soon be acquired by prosper marketplace .

with the acquisition of billguard and the rebranding of billguard app , prosper marketplace is making huge waves . the prosper daily app is the first of its kind for prosper marketplace .

as the billguard app has merged to become the prosper daily app , there seems to be one important change . in the past , billguard was a free expense tracking app .

( prosper daily ) billguard vs . mint | 2017 comparison | budget software reviews & competition

, billguard is starting to go truly global with its first launch outside of north america .

yes , from today , consumers in the uk , australia and new zealand can use billguard too . if you’re new to billguard , here’s a quick recap of how it works .

for its part , billguard seems nothing short of ecstatic to become a part of prosper .

our core mission is to use data to save people money . — billguard ceo yaron samid

billguard is a crowdsourced intelligence platform that actively tracks spending and generates grey charge alerts by listening to what millions of people are saying about credit and debit card charges nationwide . billguard users sh

the deal is mostly in cash , with some stock included as retention incentives for billguard’s staff .

billguard posted a video " help ! i can ' t add my account . " on youtube

enter billguard , who forevermore shall be known as the fairy godmother of personal finance . billguard watches over you , warns you of trouble , and gently encourages you to make the right choices .

( prosper daily ) billguard vs . mint | 2017 comparison | budget software reviews & competition – advisoryhq

in 2016 , billguard was advisoryhq ' s highest ranked “most powerful financial protection and monitoring app of the year . ” this isn ' t surprising , since billguard has been a superior personal finance software .

billguard , a personal finance analytics application and a subsidiary of prosper marketplace , on tuesd . . .

billguard and experian unveil partnership for identity protection at money2020 , 2014on november 4 , ex . . .

in other words , all problematic charges or complaints go into the billguard server and every user who has an account at billguard gets an update about the problem if it is relevant to the user’s purchasing history .

billguard reviews show that the billguard app is an easy - to - use monitoring app that provides a tremendous amount of value by helping you to quickly detect and minimize fraudulent transactions on your credit or debit cards .

( the paypers ) marketplace lender prosper has acquired personal finance app billguard for usd 30 milli . . .

back in september we announced that billguard would be acquired by prosper marketplace . if the courts . . .

while billguard has certainly seen its own success , the billguard app has recently been acquired and rebranded as the prosper daily app . as a part of prosper marketplace , how will it compete with leading financial planning software like

because the merger is still new , there are plenty of people who are asking questions about the billguard app and looking for billguard reviews , without knowing that this personal finance software is now a part of prosper daily .

while the billguard app has been rebranded with the merger , the functionality remains the same : as prosper daily , the billguard app continues to offer budget software , expense tracking , credit monitoring , and alerts for potential fraud .

over all , according to prosper , billguard customers on average use the service two to three times a week .

billguard was a personal finance analytics app that empowered consumers to control , protect and do more with their money .

note : billguard is currently only available for ios , but plans are in the works for an android version .

we reviewed what consumers were saying about the billguard app on major review and download platforms like itunes and google play .

in essence , billguard ( prosper daily ) is designed to protect and alert , while mint is designed to manage .

still , if you’re at all wary of handing your bank details over , you’re best not using billguard at all .

billguard is a service for tracking your spending and monitoring your credit , and an android app is a . . .

as prosper daily , we couldn ' t find any specific information on the app ' s security features . it ' s safe to assume that the billguard app would retain its original security , which is what we will be using in this billguard review . based on previous data , the billguard app ( prosper daily app ) is certainly safe to use .

personal capital is billguard ' s # 2 competitor . personal capital was founded in 2009 , and its headquarters is in san carlos , california . personal capital competes in the application software industry . personal capital has 172 more employees than billguard .

while the billguard app ( prosper daily app ) offers both free and paid versions , the mint app is completely free .

choosing between the prosper daily app ( billguard app ) or the mint app will inevitably come down to personal financial goals .

you can download billguard for ios and android now , in the us , canada , uk , australia and new zealand .

the prosper daily app will offer billguard’s budgeting and spending tracking services , alerts for potential fraudulent charges , and credit monitoring .

billguard has employees and is the last highest among it ' s top 10 competitors . the top 10 competitors average 894 .

san francisco - - ( business wire ) - - billguard , a personal finance analytics application and a subsidiary . . .

billguard is one of the best ways for you to track your spending costs , and protect your cards from fraud and errors .

integrating billguard into a bank ' s online and mobile banking is as easy as adding a snippet of javascript , samid adds .

back in september , peer - to - peer ( p2p ) lending platfrom prosper marketplace acquired billguard , a crow . . .

all joking aside , billguard truly is groundbreaking . the company has been around for the past few years , but for those who aren’t familiar , billguard is essentially antivirus for bills . basically , the app scans a user’s credit and debit card statements daily looking for erroneous or deceptive charges . if any erroneous charges are found , the user is notified and billguard helps get their money back . billguard uses crowd - sourced big data analytics to acquire collective knowledge about millions of consumer’s billing complaints to merchants and their banks .

mint software is seen as one of billguard ' s top competitors . mint software was founded in mountain view , california } in 2006 . mint software is in the internet software industry . compared to billguard , mint software generates $ 1 . 7m more revenue .

even if you don’t recognize a charge on your statement , you can easily get details through billguard ' s community - edited information .

as such , when comparing billguard vs . mint , we will really be talking about the prosper daily app vs . the mint app .

the billguard app ( prosper daily app ) provides real - time displays of your credit / debit card charges as soon as they occur .

billguard ( prosper daily ) makes it very easy for you to verify a charge or flag new charges on your credit and debit cards .

additionally , once your card is on file , billguard will scan that account daily and email you if it finds any questionable charges . you can also set up notifications to have billguard email you about suspicious charges , new recurring payments and data breaches that might affect your accounts .

billguard ' s revenue is the fourth highest among it ' s top 10 competitors . the top 10 competitors average $ 189 . 9m .

as with the u . s . version , billguard remains free to use in these new countries , too . in a past life billguard charged a subscription fee for multiple card tracking , but now it ' s totally free and totally unlimited . if you ' re not familiar , billguard links to your card accounts on a read - only basis to pull in your transaction history and has some pretty significant backing .

billguard had put out feelers that it was interested in potentially selling itself , prompting mr . vermut and his team to move quickly . helping them was itzik cohen , prosper’s chief business officer , who is also a former israeli pro basketball player well - known to billguard’s israeli founders .

since its inception in 2010 , the billguard app has been a trusted piece of expense tracking software , acquiring over 1 . 3 million users .

still , billguard is adding employees in dribs and drabs — currently hiring two sales folks in rented office space in manhattan ' s columbus circle .

billguard helps you detect unwanted , inaccurate or fraudulent charges on your credit card statements , and stay on top of your finances . if you aren’t already in the habit of reviewing your credit card transactions one - by - one at least once a month , billguard might help you save money .

merging two companies takes time , and it may be another year until consumers recognize the billguard budget software as synonymous with prosper daily personal finance software .

billguard utilizes bank - level aes 256 - bit encryption and all data processing is performed on isolated servers that have no direct access to the internet .

as of last month , billguard also issues personalized data - breach alerts , that automatically inform you when a business you’ve shopped at has been breached .

with employees on two continents and software that ties together merchants and consumers , billguard is trying to solve one big problem — shady credit card charges .

< a href = " urltoken " > billguard < / a > has come a long way in a short time . the company launched its s

click here to download the complete report , or for a quick overview of the findings and billguard ' s solution an infographic can be viewed here .

if you want to have the highest levels of protection for your identity and credit card activity , you will want to consider prosper daily ( billguard ) .

yet to date , billguard has not announced any bank customers . and samid says he can ' t even discuss how many it ' s talking to .

the deal for the five - year - old billguard came together in about six weeks , aaron vermut , prosper’s chief executive , said in an interview .

ultimately , the billguard app ( prosper daily app ) is focused less on budgeting , and more so on protecting your financial activity and shielding against identity theft .

in the uk , billguard supports all the major banks except barclays and hsbc , while in australia and new zealand , we’re assured all major banks are supported .

finally , while billguard was once a subscription - based product , you’ll be pleased to know that as of february this year , it’s completely free to use .

are information about good and bad charges , merchant reliability and their responsiveness to billing inquiries . this shared knowledge allows billguard to quickly notify users when other community members are questioning similar charges on their credit and debit cards . if a grey charge is suspected , billguard directly connects users with merchants for expedited resolution and refund .

of course , other apps have tried to help users save money through analytics and local discounts . so what makes billguard think it can succeed where they’ve failed ?

with its new data breach alerts , billguard will send a push notification to users whenever one of their cards is suspected to have been obtained by hackers . due to the number of charges and amount of data it sees , billguard finds that it can identify and notify users with affected accounts more quickly than the merchants themselves .

if you don’t recognize the charge , you can instruct the billguard app ( prosper daily app ) to perform additional due diligence by contacting the merchant for additional information .

two years in the making , the billguard iphone app is the culmination of the company ' s pioneering work , crowdsourcing and analyzing millions of consumer - disputed transactions .

billguard ( prosper daily ) is one of the fastest - growing expense tracking apps that automatically monitors your credit / debit card expenses and quickly pinpoints suspicious activities and charges .

billguard flags merchants on your credit card statements who frequently charge consumers for products or services they ' ve either forgotten about or they didn ' t know they were requesting .

when it comes to comparing billguard reviews and mint reviews , both apps are in steep competition . in fact , they are nearly neck - in - neck on both platforms .

still , the paid version of the billguard app ( prosper daily app ) provides essential features that mint does not , like credit fraud protection , insurance , and identity restoration .

the billguard iphone app seeks to make identifying those charges easier by highlighting new questionable charges users might get . while the billguard web product was designed mainly as a set - it - and - forget - it type of application , the iphone app hopes to keep users engaged with push notifications , letting them know of questionable charges as they pop up .

under the prosper brand , billguard’s services won’t change much . already users have the option to “optimize” their credit through a button in the app that links to prosper’s lending service .

the internet - based loan marketplace plans to announce on thursday that it has purchased billguard , a start - up that helps customers manage their money and protect their financial identity .

to determine how the prosper daily app ( billguard app ) will stack up against big financial planning software , we began by reviewing the services and features offered through mint budget software .

the new billguard app , which is available for both android phones and tablets , builds on all the features that the company had previously built into system , and adds to them .

“…bank - level security to ensure your data is kept private and secure . we require you to set a four - digit pin for your billguard account and encrypt all communication . ”

with the rebranding , the former billguard becomes prosper’s first mobile app and is the company’s first beachhead into what chief executive aaron vermut hopes will be a broader suite of mobile products .

prosper marketplace , the marketplace lender focused on refinancing and credit rehabilitation , has re - launched its billguard app ( acquired last september ) under its own brand as prosper daily . with

with spend analytics , billguard is beginning to move from being just a “personal finance security” company to also offering personal finance management tools . in other words , it’s entering mint territory .

there’s nothing like a well - executed product launch to get the breakaway team’s collective adrenalin pumping . the recent launch of the billguard ios app proved to be exceptionally exciting and rewarding .

billguard ' s engine , heralded by online banking report as " one of the top online banking innovations of all time , " has identified over $ 50 million in grey charges so far . " our data shows that if every american cardholder used the billguard iphone app , the total annual savings in grey charges could top $ 7 billion , " said ouzan .

when the billguard app ( prosper daily app ) flags such a transaction , you are notified and provided with the option of validating / confirming that the charge ( s ) is valid .

bottom line : billguard flags merchants on your credit card statements who frequently charge consumers for products or services they ' ve either forgotten about or they didn ' t know they were requesting .

about billguard : billguard is the transaction intelligence network™ enabling trusted commerce via credit cards , debit cards and digital wallets , by harnessing the inputs of millions of consumers and merchants and financial service providers . this crowdsourced knowledge empowers consumers to intelligently monitor their spending and resolve unwanted " grey charges " directly with merchants via billguard ' s mobile app or their bank ' s online statements , saving everyone time and money . billguard has won numerous top industry awards and was named one of the top banking innovations of all time in 2012 by online banking report . the company has offices in new york city and tel aviv and is backed by prominent investors including bessemer venture partners , khosla ventures , eric schmidt ' s innovation endeavors and peter thiel ' s founders fund .

billguard has headquartered its marketing , sales and business development in nyc . it was the logical choice for us , given that the billguard service merges technology with finance to give consumers the first tool to help them save money by identifying grey charges and resolving billing disputes . we are proud to be in a city that is home to the world’s largest financial institutions and most dynamic technology innovators .

as a step further in ensuring that the billguard app is safe , the firm’s systems are monitored by their own security staff 24 / 7 and audited daily by verisign and mcafee ' s hackersafe .

it ' s clear that mint is a major competitor for the billguard app , even after becoming the prosper daily app . the crucial distinction between the two apps comes down to pricing and core features .

two years ago , billguard launched to help consumers identify fraudulent charges on their credit cards . now it ' s hoping to save them money with the launch of a new iphone app determined to identify and

billguard offers spending analytics , too . this will let you break down your spending categorically , and let you see where you might be overextending yourself . this should help you to reform your spending habits .

you can grab this latest version now from the app store link below . if billguard is a favorite of yours , be sure to let folks in these new countries now what you love about it !

billguard , the leading personal finance protection company , today unveiled its free app for iphone , offering the only tool for combatting the $ 14 billion dollars lost by american cardholders to unwanted " grey charges . "

this part may make some people feel a little queasy , after all you’re handing over your precious bank details to a third - party . first up , billguard itself is a read - only service , so you ( or anyone else ) won’t be able to make any transfers with the app itself . however , this doesn’t circumvent the fact that you are still handing your details over . but billguard says it uses :

the user interface shows all your transactions on each card for the preset time range you select : 7 days , 30 days , 90 days , this month , last month , this year or all time . you’ll also see billguard’s assessment of how many transactions are ok and how many are questionable . billguard prioritizes these transactions for review , too . you can then go over the questionable charges for possible errors or fraud .

billguard ' s home page is a dashboard that displays a small window and four navigational buttons . your total credit card debt incurred so far in the current month appears in the window , along with your balance .

billguard is expanding its reach with the launch of an android app , and also adding a new feature that will alert users when their cards have been affected by a target - style data breach . the new billg

in addition to these protections , billguard has a few other innovative services . you can link your credit cards and debit cards to the app and it will monitor your transactions . if you enable geolocation features on your phone , you will be at the cutting edge of fraud prevention . if billguard sees that you are in new york , but a gas station charge is being attempted in los angeles , you would be alerted .

it all comes down to the engagement the company sees from users , according to samid . personal finance management apps normally see users sign up and quickly lose interest once the novelty wears off . but billguard is seeing its users open up the app an average of four times a week . in the same way that people clean out their inboxes , billguard users are going there to clear away questionable charges , almost every day .

as one of the fastest - growing news media sources that performs detailed reviews of financial platforms , apps , software , and advisors , we frequently run into questions about billguard and its rebranding as the prosper daily app .

arriving for us consumers way back in 2010 , billguard touts itself as the world’s first ‘people - powered antivirus system for bills’ . its predictive algorithms alert you when there’s unexpected charges such as hidden fees , billing errors , scams and fraud on your credit card or debit card , while it also serves up warnings when a similar dubious charge has been flagged by other users . as such , the ‘billguard brain’ becomes more accurate over time .

billguard says it is on course to pass the million - users mark , and is adding 2 , 500 more each day . since launch , it claims to have flagged more than $ 60 million in suspect charges .

you’ll need to register an account with billguard , and you must set yourself up with a 4 - digit passcode to access the app . after that , you tap to add your debit or credit card ( s ) .

in many cases , people forget they signed up for something , which merchants are counting on , says mary anne keegan , chief marketing officer for billguard . and consumers often don ' t dispute the charges , she says .

with that in mind , billguard is perhaps based on the same premise of probabilistic modeling ( gathering unstructured data and drawing algorithmic conclusions ) that the israeli army might use to make decisions on how best to protect its borders .

billguard retained aite group , a leading research and advisory firm with expertise in financial services , to conduct the study to examine the grey charge problem among us debit and credit cardholders and the service cost impact on card issuers .

based on billguard - provided non - personally identifiable information for 4 , 817 randomly selected billguard users from january to december 2012 , this impact note by senior analyst ron shevlin sizes the grey charge problem among u . s . cardholders ( debit and credit ) and the service cost impact on issuers . the piece also defines the 11 types of grey charges and shows how it is in issuers ' best interest to help cardholders monitor and avoid grey charges .

three days and 32 startup pitches later , the winner of techcrunch disrupt has been determined . out of the 30 startups and two audience choice winners , we whittled the list down to six finalists , which include billguard , ccloop , do @ , getaround , invoiceasap , and sonar . without further ado , the two runners - up are billguard and sonar ( that’s the first time we’ve had two runners - up ) . and the winner is… . getaround !

as we said before , there are countless finance apps out there , but so far billguard is the only one that offers a complete personal finance experience . and like a fairy godmother , they will always have the user’s back .

billguard , an israeli startup that helps people fight credit card fraud by using “the wisdom of the crowds , ” was recently introduced to the public , after it receives an initial funding of $ 3 million from american investor funds .

simultaneous to the launch , the billguard ios app was featured in the apple app store . this featured status—combined with the widespread media coverage that was hard to avoid—helped push the app into the coveted # 1 position in its category .

anyway , that’s all functionality that billguard had previously enabled . but now , thanks to all the information it has about charges its users have made , it can also alert them when their cards are at risk of a data breach .

features and functionality aside , billguard is a beautifully designed app that adopts familiar mailbox - like swiping gestures to let you navigate your way through the app . it’ll likely find itself many new fans in the wake of its international expansion .

he began billguard in 2009 after he noticed a ridiculous $ 9 . 99 recurring charge on his wife ' s credit card bill . after some googling he figured out it was a concert ticket vendor scam that cost him 60 bucks .

as such , i am always interested when i run into platforms like billguard , mint ( sold to intuit for $ 170 million ) , prosper daily , and a wide range of other highly innovative tools that are disrupting the financial segment .

in september , 2015 prosper acquired billguard , a company that created a mobile personal finance application . the application allowed users to track financial transactions and prevent fraud . today , prosper announced the end of the billguard brand and introduced a new application with many changes . the new app called prosper daily is available today on apple and android devices . peter and i spoke with itzik cohen , chief business officer to learn more about the new application and how it fits into prosper loans .

today , we speak with yaron samid , co - founder and ceo of billguard , a free personal finance security service that uses crowdsourced big - data analytics to identify deceptive , erroneous and unauthorized charges to your credit or debit card bills .

the gist of billguard from here on in is this : you stipulate which spending categories you wish to view ( e . g . ‘clothing’ , ‘cash’ , ‘eating out’ ) , and set up notifications for when new charges hit your account , which can be daily or weekly . while you can use billguard to view how much you’ve spent on various things , otherwise known as ‘budgeting’ , this is not its main selling point . security and saving money is the name of the game here .

samid instantly began searching for the expertise to build the system . he found that in ouzan . a french - born 22 - year - old , his first day at billguard was his last in the israeli army after a five years stint .

although move from analogue banking to digital is disrupting the ground beneath their feet , the banks still do have one advantage : they hold a lot of core data . and it ' s this data that companies like billguard would like access to .

if everyone went over their credit card statements with a fine - tooth comb and reported any questionable or unwanted charges immediately , there wouldn ' t be much need for an iphone app like billguard . but not everyone does . i know i don ' t . billguard , described by its developer as a " personal finance security service , " is a smart , useful , innovative iphone app ( also available on android ) that ' s simple—almost fun—to set up and use . it displays your credit card charges as they occur , flagging any that have been frequently reported by members of its network as questionable or unauthorized . you can either confirm that those charges are authorized or ask billguard , via a simple automated reporting system , to contact the merchant on your behalf .

i have historically used the free option , depending upon early detection from creditkarma and my own ability to manage the resolution process . after doing this research , i am going to buy a zander membership for my mother and am tempted by billguard for myself .

in conjunction with announcing the new mobile app for billguard—a popular online service that scans users’ credit and debit card bills , alerting them to potentially deceptive and unwanted charges that are known as “grey charges”—the company teamed with research firm aite group to issue the finance industry’s first definitive research study on grey charges . the findings of this study were incredibly eye opening . the grey charges news got a lot of attention , and drove massive attention to the only service available to help credit card holders identify grey charges , billguard .

the free app intelligently prioritizes noteworthy , recent and recurring charges across all of a cardholder ' s credit and debit cards . " it ' s like a smart inbox for your money , " said samid . " the app uses crowdsourced analytics from billguard ' s national transaction intelligence network™ to help users quickly spot and recognize charges deemed questionable by other cardholders on their cards . as users archive verified charges and trusted merchants with a single finger - swipe , billguard gets smarter , customizing their priority list with the charges they want to review . to handle billing inquiries and disputes billguard completely bypasses the costly and inefficient chargeback networks to connect cardholders directly to merchants for free , expedited resolution . it ' s a classic win - win - win for consumers , merchants and banks . "

according to billguard ceo yaron samid , the company has found that its analytics are the main value prop for the app , but it’s the tracking feature that’s the lead utility , and what keeps users coming back an average of 4 . 5 times a week .

collectively , consumers paid $ 14 . 3 billion in unwanted charges last year , according to the survey commissioned by billguard , an online service and app that tracks and alerts consumers to these kinds of charges and helps users dispute them . it found that one in three american card holders is hit with these " gray charges " at an average of $ 215 per person per year . the survey analyzed an anonymous sampling of a year ' s worth of credit and debit card transactions from nearly 5 , 000 billguard users .

billguard was a finalist at techcrunch disrupt a few years ago , and since has raised $ 13 million in funding from investors that include khosla ventures , founders fund , eric schmidt’s innovation endeavors , bessemer venture partners , ia ventures , saul klein and joe lonsdale .

* to celebrate its launch week , billguard is making its premium upgrade , which supports 10 cards , available for a one - time in - app purchase of $ 9 . 99 . download the app here . continuing its mission to protect consumers from grey charges , billguard today also released the 2013 industry report on grey charges , a first - of - its kind study revealing that american cardholders were hit with $ 14 . 3 billion in deceptive grey charges in 2012 . click here for more information about the report .

if you aren ' t careful , these fees can amount to some big bucks . billguard reported that about one third of cardholders in its sample paid $ 100 or more in grey fees during 2012 , and almost one in 10 paid more than $ 500 .

billguard is a personal finance security platform that enables users to track and monitor their spending across credit and debit card transactions . founded in 2009 , it has its headquarters in new york city . as of october 2014 , it reports that it has f . . .

prosper marketplace , a peer - to - peer lender that has funded more than $ 4 billion in personal loans , announced thursday that it will acquire billguard , a spending - and - credit - tracking app , for $ 30 million . billguard works by letting its users track their spending , monitor their credit , set up fraud alerts and , via crowd - sourced data , flag unauthorized charges ; it says that it has helped its 1 . 3 million users flag more than $ 70 million in unauthorized charges since its inception in 2010 .

the alerts are useful enough , but since billguard also tracks your credit cards and accounts for suspicious charges ( and even so - called " grey charges " you may not otherwise notice ) , you can opt to keep an eye on things and act if you see anything strange . for its part , the new android app looks great and includes all of billguard ' s features , including budgeting tools , account overviews , and more . hit the link below to learn more about the new feature , or to download the android app at google play .

in either case , samid said billguard is going to be ultra picky about the coupons that it sends to users . and since it’s scanning the web for new discounts and it’s not working with merchants to pitch discounts to users , it’s not incentivized to spam them with offers .

if you follow financial news , you know that last year there were numerous data breaches at major corporations like target . in response , billguard has added a watchdog feature to alert you via email and phone when these occur , in case you don ' t hear about it quickly .

the event , held at the british museum , will feature speakers including bbva chairman and ceo , francisco gonzález . billguard founder and cto raphael ouzan will be speaking in the " innovating by design " session alongside hiroki takeuchi of gocardless , taavet hinrikus of transferwise and valentin stalf of number26 .

the top 10 competitors in billguard ' s competitive set are mint software , personal capital , credit karma , lifelock , sigfig , credit sesame , mint bills , level money , identity guard and mcafee . together they have raised over 6 . 5b between their estimated 9 . 8k employees .

if you want the highest level of protection for the lowest cost , you might want to consider downloading the app billguard , which was just acquired by prosper . for $ 9 . 99 a month , or $ 83 . 88 a year if you pay all at once , you receive billguard ultimate . with this product , all three bureaus will be monitored daily for changes . you will be given access to a us - based recovery agent to manage the process from beginning to end if your identity is compromised . and a $ 1 million insurance policy is available as well .

for example , billguard might detect two $ 7 . 95 charges for amazon kindle on december 26 and ask you if one is a duplicate charge . you can then log into your amazon account and see if you actually bought two kindle books on the same day that were identical in price .

to confirm that they made a purchase , users simply swipe right on charges as they appear in the app . if , however , they don’t recognize a charge or wish to dispute it , billguard makes it easy to report those they believe to fraudulent or contact the merchant from inside the app .

" i was looking for a system of collaborative data analytics , but i found it in a parallel industry — anti - spam " software , says samid . " we modeled billguard after this anti - spam methodology and we built the consumer service first . that ' s how we started . "

the smart savings feature notifies users of discounts or coupons that they may not know about . since billguard knows a user’s purchase history , the offers will be relevant to their day to day life . a user can also accept or reject coupons , and the app will then adjust its behavior accordingly .

android / ios : billguard , the service that already notifies you of questionable charges and monitors your credit for you , now also offers personalized data breach alerts . now , if a bank , credit card , or retailer you frequent loses data in a security breach , the app will notify you immediately .

two years ago , billguard launched to help consumers identify fraudulent charges on their credit cards . now it’s hoping to save them money with the launch of a new iphone app determined to identify and dispute so - called “grey charges” — that is , charges that they might have agreed to but forgot about .

our pr strategy was built around the powerful one - two punch of defining the massive grey charge problem via industry research—which was quantified at over $ 14 billion in 2012—and connecting the concept to the highly effective and easy - to - use billguard ios app solution via media and analyst relations and social media .

a simple , friendly solution personal finance management applications are just getting started when they connect to your financial institution and download transactions . they have many other features . billguard is much less complex , but it ' s still very smart , in a couple of ways . first , it draws on the experience of other consumers to let you know when what you ' re experiencing with a particular merchant is widespread . and second , it has isolated one element of personal finance that can get lost in the noise of more robust applications . billguard provides a quick and easy solution to one clearly - defined problem–gray charges . which are you more likely to do , pore over your printed or downloaded credit card statement , or pull out your iphone and spend a minute or two with a cool app ? billguard is one personal finance app i ' m going leave on my iphone long after i ' ve finished testing it .

tracking is also important , since only about a third of all fraudulent charges are caught by the banks themselves . the other two - thirds are reported by credit card owners themselves . so far , billguard says that its users have reported more than $ 60 million worth of fraudulent charges identified through the app .

" these gray charges are not illegal ; they ' re just kind of unethical and a little bit questionable , " says ron shevlin , senior analyst at aite group , which conducted the survey for billguard . " and many times it ' s the consumer ' s behavior that triggers these gray charges . "

it is not only direct criminals , but legitimate merchants who sneak deceptive and unwanted charges that most people will miss . just like google uses collective power to detect spam , billguard provides the first - ever service to identify and resolve those grey charges by harnessing the knowledge of millions of consumers reporting bad charges .

billguard analyzes pools of data and , if it detects something suspicious such as random fees or ‘grey’ charges ( e . g . a subscription auto - renewal ) , it raises a red flag and asks you whether you want help recognizing it . it also allows you to contact the merchant directly through the app .

shevlin hopes card issuers will soon be required to monitor the charges in some way . and billguard is working with the consumer financial protection bureau to supply data about the prevalence of deceptive marketing practices as part of an initiative cfpb launched last fall to encourage " consumer - friendly innovation " in the financial services industry .

to use this free service , you sign up for an account using your email address , then register the credit and debit cards you want to monitor . choose the bank that issues your card , then enter your login credentials . billguard will scan your accounts for hidden fees , billing errors , scams and fraud .

that starts with a new design that’s built to better highlight how users are spending their money at a glance , while also showing how much more or less they’ve spent versus a usual month . bringing that spend analytics front and center while making it easier to understand was one of the key areas of focus for billguard .

tap the push pin , and another small window of options opens . if you click the help me recognize this button , billguard provides links that let you ask a friend about it via email or text message . you can also start a search in google from that point to try and figure out what the charge is . the report / contact merchant button takes you to the report charge window , where you can select your problem from a list that includes stolen card , forgotten charge , and hidden fee . you ' ll be able to enter text expanding on that , and then you can authorize billguard to contact the merchant for you .

billguard is straightforward and easy to use and limited in what it does , but it does offer a more inclusive battery of services these days . it won ' t give you an overall picture of your financial situation , but in addition to keeping your accounts safe , it might help you stick to a budget , too .

in order to engage with and retain these younger customers the banks need to figure out a way to focus on the consumer experience , making it easier and more pleasant . ouzan says that means continuing to develop products like billguard that can be used in an ongoing basis to transform the banking experience for the benefit of consumers .

ny has always been “the great american melting pot . ” it has a long , rich history of enabling entrepreneurs to make their dreams become a reality and businesses to flourish and grow . for billguard , ny was a logical choice , given that it is home to the world’s largest financial institutions and most dynamic technology innovators .

the update comes on the heels of billguard ' s new android app ( the service was previously ios only ) so you get the benefit of improved security as well as the ability to track your finances on the go . the video below is a good introduction to the new app . the service tooks the initiative to start tracking security breaches after the big target incident back in december , and now whenever something similar happens to a company you shop with , or a bank you have an account with , billguard will alert you via push notification and via email . it ' ll also include instructions and suggestions for what you should do as a result .

gray charges and security breaches billguard doesn ' t promote itself as an identity theft - prevention tool , though it can work like one if you check it regularly . rather , its mission is to help you avoid " gray charges , " unwanted hits on your credit cards . maybe you signed up for something and forgot about it . or maybe the merchant used misleading , deceptive language or hid a recurring charge in fine print that you ' re unlikely to have seen . billguard claims that u . s . cardholders spend $ 14 . 3 billion in gray charges annually , so it ' s a good idea to keep an eye out for them .

of those who incurred gray charges last year , the largest percentage dealt with charges totaling $ 20 to $ 50 for the year , the billguard report shows . the average individual charge was slightly higher , though , at $ 61 , likely because some of the less prevalent types of charges can be for higher amounts , keegan says .

billguard has developed a “collective vigilance , or people - powered solution , ” that can take an alert raised by one of their users and send it to every other user that might also be affected . the company warns them about excess credit card charges , billing errors , fraud , or other charges of which they are not aware .

the problem is that most customers don’t pay enough attention to their credit card accounts to know that they’re there or dispute them . according to a study conducted using billguard data , there are approximately 233 million grey charges posted to u . s . credit cards every year , resulting in about $ 14 . 3 billion lost by consumers annually .

billguard has raised $ 13 million from investors that include khosla ventures , founders fund , eric schmidt’s innovation endeavors , bessemer , ia ventures , saul klein , and joe lonsdale . the company now has 23 employees , most of which are based in tel aviv , israel… but it’s looking to hire more . ( * hint , hint * )

“our core mission is to use data to save people money , ” billguard ceo yaron samid told me via skype . “we’re really good at saving people from the bad stuff , and now we want to find the good stuff… [ the app ] is like the perfect accountant running in the background and trying to find ways to save money . ”


dr. stephen c. tweedie is a software developer who is known for his work on the linux kernel , in particular his work on filesystems .

after becoming involved with the development of the ext2 filesystem working on performance issues , he led the development of the ext3 filesystem which involved adding a journaling layer to the ext2 filesystem .

for his work on the journaling layer , he has been described by fellow linux developer andrew morton as " a true artisan " .

born in edinburgh , scotland in 1969 , tweedie studied computer science at churchill college , cambridge and the university of edinburgh , where he did his thesis on contention and achieved performance in multicomputer wormhole routing networks .

after contributing to the linux kernel in his spare time since the early nineties and working on vms filesystem support for dec for two years , tweedie was employed by linux distributor red hat where he continues to work on the linux kernel .

tweedie has published a number of papers on linux , including design and implementation of the second extended filesystem in 1994 , journaling the linux ext2fs filesystem in 1998 , and planned extensions to the linux ext2/ext3 filesystem in 2002 .

tweedie is also a frequent speaker on the subject of linux kernel development at technical conferences .

amongst others , he has given talks on linux kernel development at the 1997 and 1998 usenix annual technical conferences , the 2000 ukuug conference in london , and he gave the keynote speech at the ottawa linux symposium in 2002 .

stephen tweedie

stephen tweedie <EOT> stephen w . tweedie associate professor emeritus department of geography oklahoma state university stillwater , oklahoma 74078 - 4073 office : 358 murray hall phone : ( 405 ) 744 - 6250 fax : ( 405 ) 744 - 5620 e - mail : stephen . tweedie @ urltoken

posted in programming , technology . tags : advantages of ext3 , availability , data integrity , easy transition , ext2 , ext3 , ext3 vs ext2 , file systems , journaling , red hat linux , speed , stephen tweedie . leave a comment »

the original presentation of this talk occurred in room a of the ottawa linux symposium , ottawa congress centre , ottawa , ontario , canada on the 20th of july , 2000 at 13 : 45 local time . this presentation was given by dr . stephen tweedie .

tweedie & associates consulting engineers can provide our award - winning geothermal heat pump design services for your project . 506 - 383 - 8223

rémy card , laboratoire masi - - institut blaise pascal , e - mail : card @ masi . ibp . fr , and theodore ts ' o , massachussets institute of technology , e - mail : tytso @ mit . edu , and stephen tweedie , university of edinburgh , e - mail : sct @ urltoken

r . card , t . y . ts ' o , and s . tweedie , ` ` design and implementation of the second extended filesystem , ' ' in

stephen tweedie , p . eng . , leed ap , cbcp is the principal of tweedie & associates consulting engineers ltd . ( tace ) and is a engineer with 31 years of experience . prior to establishing tace , stephen worked as a mechanical design engineer with the province of nova scotia , dept . of government services where he was involved in the design and project supervision of hvac , plumbing , fire protection and medical gas systems in public buildings , including government offices , and hospitals . he later worked as a process engineer with combustion engineering superheater ltd . where he was responsible for supervision of process control and equipment maintenance in nuclear fuel bundle production for candu reactors .

working for dec for two years , stephen worked on vms kernel internals for high - availability clustered filesystems . he is now employed full - time by red hat , which lets him work on linux exclusively .

stephen has been awarded the 1999 ashrae technology award for institutional buildings , for outstanding achievement in energy - efficient building design for the nova institution , a federal women ' s correctional facility located in truro , nova scotia .

ext3 is a journaling filesystem developed by stephen tweedie . it is compatible to ext2 filesystems ; actually you can look at it as an ext2 filesystem with a journal file . the journaling capability means no more waiting for fsck’s or worrying about metadata corruption . what is most noticeable is that you can switch back and forth between ext2 and ext3 on a partition without any problem : it is just a matter of giving the mount command the right filesystem type .

stephen has been involved with the development of the linux kernel since its early days . his work has been primarily on the filesystem and virtual memory code , with miscellaneous contributions all over the kernel . however he never goes near the network code . his recent and current projects include several high - end features such as raw i / o , fast zero - copy filesystem i / o and high availability .

this paper was first published in the proceedings of the first dutch international symposium on linux , isbn 90 - 367 - 0385 - 9 .

linux is a unix - like operating system , which runs on pc - 386 computers . it was implemented first as extension to the minix operating system

and its first versions included support for the minix filesystem only . the minix filesystem contains two serious limitations : block addresses are stored in 16 bit integers , thus the maximal filesystem size is restricted to 64 mega bytes , and directories contain fixed - size entries and the maximal file name is 14 characters .

we have designed and implemented two new filesystems that are included in the standard linux kernel . these filesystems , called ` ` extended file system ' ' ( ext fs ) and ` ` second extended file system ' ' ( ext2 fs ) raise the limitations and add new features .

in this paper , we describe the history of linux filesystems . we briefly introduce the fundamental concepts implemented in unix filesystems . we present the implementation of the virtual file system layer in linux and we detail the second extended file system kernel code and user mode tools . last , we present performance measurements made on linux and bsd filesystems and we conclude with the current status of ext2fs and the future directions .

in its very early days , linux was cross - developed under the minix operating system . it was easier to share disks between the two systems than to design a new filesystem , so linus torvalds decided to implement support for the minix filesystem in linux . the minix filesystem was an efficient and relatively bug - free piece of software .

however , the restrictions in the design of the minix filesystem were too limiting , so people started thinking and working on the implementation of new filesystems in linux .

in order to ease the addition of new filesystems into the linux kernel , a virtual file system ( vfs ) layer was developed . the vfs layer was initially written by chris provenzano , and later rewritten by linus torvalds before it was integrated into the linux kernel . it is described in

after the integration of the vfs in the kernel , a new filesystem , called the ` ` extended file system ' ' was implemented in april 1992 and added to linux 0 . 96c . this new filesystem removed the two big minix limitations : its maximal size was 2 giga bytes and the maximal file name size was 255 characters . it was an improvement over the minix filesystem but some problems were still present in it . there was no support for the separate access , inode modification , and data modification timestamps . the filesystem used linked lists to keep track of free blocks and inodes and this produced bad performances : as the filesystem was used , the lists became unsorted and the filesystem became fragmented .

as a response to these problems , two new filesytems were released in alpha version in january 1993 : the xia filesystem and the second extended file system . the xia filesystem was heavily based on the minix filesystem kernel code and only added a few improvements over this filesystem . basically , it provided long file names , support for bigger partitions and support for the three timestamps . on the other hand , ext2fs was based on the extfs code with many reorganizations and many improvements . it had been designed with evolution in mind and contained space for future improvements . it will be described with more details in

when the two new filesystems were first released , they provided essentially the same features . due to its minimal design , xia fs was more stable than ext2fs . as the filesystems were used more widely , bugs were fixed in ext2fs and lots of improvements and new features were integrated . ext2fs is now very stable and has become the de - facto standard linux filesystem .

files are represented by inodes , directories are simply files containing a list of entries and devices can be accessed by requesting i / o on special files .

each file is represented by a structure , called an inode . each inode contains the description of the file : file type , access rights , owners , timestamps , size , pointers to data blocks . the addresses of data blocks allocated to a file are stored in its inode . when a user requests an i / o operation on the file , the kernel code converts the current offset to a block number , uses this number as an index in the block addresses table and reads or writes the physical block . this figure represents the structure of an inode :

directories are structured in a hierarchical tree . each directory can contain files and subdirectories .

directories are implemented as a special type of files . actually , a directory is a file containing a list of entries . each entry contains an inode number and a file name . when a process uses a pathname , the kernel code searchs in the directories to find the corresponding inode number . after the name has been converted to an inode number , the inode is loaded into memory and is used by subsequent requests .

unix filesystems implement the concept of link . several names can be associated with a inode . the inode contains a field containing the number associated with the file . adding a link simply consists in creating a directory entry , where the inode number points to the inode , and in incrementing the links count in the inode . when a link is deleted , i . e . when one uses the

command to remove a filename , the kernel decrements the links count and deallocates the inode if this count becomes zero .

this type of link is called a hard link and can only be used within a single filesystem : it is impossible to create cross - filesystem hard links . moreover , hard links can only point on files : a directory hard link cannot be created to prevent the apparition of a cycle in the directory tree .

another kind of links exists in most unix filesystems . symbolic links are simply files which contain a filename . when the kernel encounters a symbolic link during a pathname to inode conversion , it replaces the name of the link by its contents , i . e . the name of the target file , and restarts the pathname interpretation . since a symbolic link does not point to an inode , it is possible to create cross - filesystems symbolic links . symbolic links can point to any type of file , even on nonexistent files . symbolic links are very useful because they don ' t have the limitations associated to hard links . however , they use some disk space , allocated for their inode and their data blocks , and cause an overhead in the pathname to inode conversion because the kernel has to restart the name interpretation when it encounters a symbolic link .

in unix - like operating systems , devices can be accessed via special files . a device special file does not use any space on the filesystem . it is only an access point to the device driver .

two types of special files exist : character and block special files . the former allows i / o operations in character mode while the later requires data to be written in block mode via the buffer cache functions . when an i / o request is made on a special file , it is forwarded to a ( pseudo ) device driver . a special file is referenced by a major number , which identifies the device type , and a minor number , which identifies the unit .

the linux kernel contains a virtual file system layer which is used during system calls acting on files . the vfs is an indirection layer which handles the file oriented system calls and calls the necessary functions in the physical filesystem code to do the i / o .

when a process issues a file oriented system call , the kernel calls a function contained in the vfs . this function handles the structure independent manipulations and redirects the call to a function contained in the physical filesystem code , which is responsible for handling the structure dependent operations . filesystem code uses the buffer cache functions to request i / o on devices . this scheme is illustrated in this figure :

the vfs defines a set of functions that every filesystem has to implement . this interface is made up of a set of operations associated to three kinds of objects : filesystems , inodes , and open files .

the vfs knows about filesystem types supported in the kernel . it uses a table defined during the kernel configuration . each entry in this table describes a filesystem type : it contains the name of the filesystem type and a pointer on a function called during the mount operation . when a filesystem is to be mounted , the appropriate mount function is called . this function is responsible for reading the superblock from the disk , initializing its internal variables , and returning a mounted filesystem descriptor to the vfs . after the filesystem is mounted , the vfs functions can use this descriptor to access the physical filesystem routines .

a mounted filesystem descriptor contains several kinds of data : informations that are common to every filesystem types , pointers to functions provided by the physical filesystem kernel code , and private data maintained by the physical filesystem code . the function pointers contained in the filesystem descriptors allow the vfs to access the filesystem internal routines .

two other types of descriptors are used by the vfs : an inode descriptor and an open file descriptor . each descriptor contains informations related to files in use and a set of operations provided by the physical filesystem code . while the inode descriptor contains pointers to functions that can be used to act on any file ( e . g .

) , the file descriptors contains pointer to functions which can only act on open files ( e . g .

the second extended file system has been designed and implemented to fix some problems present in the first extended file system . our goal was to provide a powerful filesystem , which implements unix file semantics and offers advanced features .

of course , we wanted to ext2fs to have excellent performance . we also wanted to provide a very robust filesystem in order to reduce the risk of data loss in intensive use . last , but not least , ext2fs had to include provision for extensions to allow users to benefit from new features without reformatting their filesystem .

the ext2fs supports standard unix file types : regular files , directories , device special files and symbolic links .

ext2fs is able to manage filesystems created on really big partitions . while the original kernel code restricted the maximal filesystem size to 2 gb , recent work in the vfs layer have raised this limit to 4 tb . thus , it is now possible to use big disks without the need of creating many partitions .

ext2fs provides long file names . it uses variable length directory entries . the maximal file name size is 255 characters . this limit could be extended to 1012 if needed .

) . normally , 5 % of the blocks are reserved . this allows the administrator to recover easily from situations where user processes fill up filesystems .

in addition to the standard unix features , ext2fs supports some extensions which are not usually present in unix filesystems .

file attributes allow the users to modify the kernel behavior when acting on a set of files . one can set attributes on a file or on a directory . in the later case , new files created in the directory inherit these attributes .

bsd or system v release 4 semantics can be selected at mount time . a mount option allows the administrator to choose the file creation semantics . on a filesystem mounted with bsd semantics , files are created with the same group id as their parent directory . system v semantics are a bit more complex : if a directory has the setgid bit set , new files inherit the group id of the directory and subdirectories inherit the group id and the setgid bit ; in the other case , files and subdirectories are created with the primary group id of the calling process .

bsd - like synchronous updates can be used in ext2fs . a mount option allows the administrator to request that metadata ( inodes , bitmap blocks , indirect blocks and directory blocks ) be written synchronously on the disk when they are modified . this can be useful to maintain a strict metadata consistency but this leads to poor performances . actually , this feature is not normally used , since in addition to the performance loss associated with using synchronous updates of the metadata , it can cause corruption in the user data which will not be flagged by the filesystem checker .

ext2fs allows the administrator to choose the logical block size when creating the filesystem . block sizes can typically be 1024 , 2048 and 4096 bytes . using big block sizes can speed up i / o since fewer i / o requests , and thus fewer disk head seeks , need to be done to access a file . on the other hand , big blocks waste more disk space : on the average , the last block allocated to a file is only half full , so as blocks get bigger , more space is wasted in the last block of each file . in addition , most of the advantages of larger block sizes are obtained by ext2 filesystem ' s preallocation techniques ( see section

ext2fs implements fast symbolic links . a fast symbolic link does not use any data block on the filesystem . the target name is not stored in a data block but in the inode itself . this policy can save some disk space ( no data block needs to be allocated ) and speeds up link operations ( there is no need to read a data block when accessing such a link ) . of course , the space available in the inode is limited so not every link can be implemented as a fast symbolic link . the maximal size of the target name in a fast symbolic link is 60 characters . we plan to extend this scheme to small files in the near future .

ext2fs keeps track of the filesystem state . a special field in the superblock is used by the kernel code to indicate the status of the file system . when a filesystem is mounted in read / write mode , its state is set to ` ` not clean ' ' . when it is unmounted or remounted in read - only mode , its state is reset to ` ` clean ' ' . at boot time , the filesystem checker uses this information to decide if a filesystem must be checked . the kernel code also records errors in this field . when an inconsistency is detected by the kernel code , the filesystem is marked as ` ` erroneous ' ' . the filesystem checker tests this to force the check of the filesystem regardless of its apparently clean state .

always skipping filesystem checks may sometimes be dangerous , so ext2fs provides two ways to force checks at regular intervals . a mount counter is maintained in the superblock . each time the filesystem is mounted in read / write mode , this counter is incremented . when it reaches a maximal value ( also recorded in the superblock ) , the filesystem checker forces the check even if the filesystem is ` ` clean ' ' . a last check time and a maximal check interval are also maintained in the superblock . these two fields allow the administrator to request periodical checks . when the maximal check interval has been reached , the checker ignores the filesystem state and forces a filesystem check . ext2fs offers tools to tune the filesystem behavior . the

the error behavior . when an inconsistency is detected by the kernel code , the filesystem is marked as ` ` erroneous ' ' and one of the three following actions can be done : continue normal execution , remount the filesystem in read - only mode to avoid corrupting the filesystem , make the kernel panic and reboot to run the filesystem checker .

an attribute allows the users to request secure deletion on files . when such a file is deleted , random data is written in the disk blocks previously allocated to the file . this prevents malicious people from gaining access to the previous content of the file by using a disk editor .

last , new types of files inspired from the 4 . 4 bsd filesystem have recently been added to ext2fs . immutable files can only be read : nobody can write or delete them . this can be used to protect sensitive configuration files . append - only files can be opened in write mode but data is always appended at the end of the file . like immutable files , they cannot be deleted or renamed . this is especially useful for log files which can only grow .

. a filesystem is made up of block groups . block groups are analogous to bsd ffs ' s cylinder groups . however , block groups are not tied to the physical layout of the blocks on the disk , since modern drives tend to be optimized for sequential access and hide their physical geometry to the operating system .

each block group contains a redundant copy of crucial filesystem control informations ( superblock and the filesystem descriptors ) and also contains a part of the filesystem ( a block bitmap , an inode bitmap , a piece of the inode table , and data blocks ) . the structure of a block group is represented in this table :

using block groups is a big win in terms of reliability : since the control structures are replicated in each block group , it is easy to recover from a filesystem where the superblock has been corrupted . this structure also helps to get good performances : by reducing the distance between the inode table and the data blocks , it is possible to reduce the disk head seeks during i / o on files .

in ext2fs , directories are managed as linked lists of variable length entries . each entry contains the inode number , the entry length , the file name and its length . by using variable length entries , it is possible to implement long file names without wasting disk space in directories . the structure of a directory entry is shown in this table :

the ext2fs kernel code contains many performance optimizations , which tend to improve i / o speed when reading and writing files .

ext2fs takes advantage of the buffer cache management by performing readaheads : when a block has to be read , the kernel code requests the i / o on several contiguous blocks . this way , it tries to ensure that the next block to read will already be loaded into the buffer cache . readaheads are normally performed during sequential reads on files and ext2fs extends them to directory reads , either explicit reads (

ext2fs also contains many allocation optimizations . block groups are used to cluster together related inodes and data : the kernel code always tries to allocate data blocks for a file in the same group as its inode . this is intended to reduce the disk head seeks made when the kernel reads an inode and its data blocks .

when writing data to a file , ext2fs preallocates up to 8 adjacent blocks when allocating a new block . preallocation hit rates are around 75 % even on very full filesystems . this preallocation achieves good write performances under heavy load . it also allows contiguous blocks to be allocated to files , thus it speeds up the future sequential reads .

to allow user mode programs to manipulate the control structures of an ext2 filesystem , the libext2fs library was developed . this library provides routines which can be used to examine and modify the data of an ext2 filesystem , by accessing the filesystem directly through the physical device .

the ext2fs library was designed to allow maximal code reuse through the use of software abstraction techniques . for example , several different iterators are provided . a program can simply pass in a function to

, which will be called for each block in an inode . another iterator function allows an user - provided function to be called for each file in a directory .

) use the ext2fs library . this greatly simplifies the maintainance of these utilities , since any changes to reflect new features in the ext2 filesystem format need only be made in one place - - in the ext2fs library . this code reuse also results in smaller binaries , since the ext2fs library can be built as a shared library image .

because the interfaces of the ext2fs library are so abstract and general , new programs which require direct access to the ext2fs filesystem can very easily be written . for example , the ext2fs library was used during the port of the 4 . 4bsd dump and restore backup utilities . very few changes were needed to adapt these tools to linux : only a few filesystem dependent functions had to be replaced by calls to the ext2fs library .

the ext2fs library provides access to several classes of operations . the first class are the filesystem - oriented operations . a program can open and close a filesystem , read and write the bitmaps , and create a new filesystem on the disk . functions are also available to manipulate the filesystem ' s bad blocks list .

the second class of operations affect directories . a caller of the ext2fs library can create and expand directories , as well as add and remove directory entries . functions are also provided to both resolve a pathname to an inode number , and to determine a pathname of an inode given its inode number .

the final class of operations are oriented around inodes . it is possible to scan the inode table , read and write inodes , and scan through all of the blocks in an inode . allocation and deallocation routines are also available and allow user mode programs to allocate and free blocks and inodes .

powerful management tools have been developed for ext2fs . these utilities are used to create , modify , and correct any inconsistencies in ext2 filesystems . the

, it can change the error behavior , the maximal mount count , the maximal check interval , and the number of logical blocks reserved for the super user .

is intended to repair filesystem inconsistencies after an unclean shutdown of the system . the original version of

was based on linus torvald ' s fsck program for the minix filesystem . however , the current version of

was rewritten from scratch , using the ext2fs library , and is much faster and can correct more filesystem inconsistencies than the original version .

program is designed to run as quickly as possible . since filesystem checkers tend to be disk bound , this was done by optimizing the algorithms used by

so that filesystem structures are not repeatedly accessed from the disk . in addition , the order in which inodes and directories are checked are sorted by block number to reduce the amount of time in disk seeks . many of these ideas were originally explored by

iterates over all of the inodes in the filesystem and performs checks over each inode as an unconnected object in the filesystem . that is , these checks do not require any cross - checks to other filesystem objects . examples of such checks include making sure the file mode is legal , and that all of the blocks in the inode are valid block numbers . during pass 1 , bitmaps indicating which blocks and inodes are in use are compiled .

notices data blocks which are claimed by more than one inode , it invokes passes 1b through 1d to resolve these conflicts , either by cloning the shared blocks so that each inode has its own copy of the shared block , or by deallocating one or more of the inodes .

pass 1 takes the longest time to execute , since all of the inodes have to be read into memory and checked . to reduce the i / o time necessary in future passes , critical filesystem information is cached in memory . the most important example of this technique is the location on disk of all of the directory blocks on the filesystem . this obviates the need to re - read the directory inodes structures during pass 2 to obtain this information .

pass 2 checks directories as unconnected objects . since directory entries do not span disk blocks , each directory block can be checked individually without reference to other directory blocks . this allows

to sort all of the directory blocks by block number , and check directory blocks in ascending order , thus decreasing disk seek time . the directory blocks are checked to make sure that the directory entries are valid , and contain references to inode numbers which are in use ( as determined by pass 1 ) .

for the first directory block in each directory inode , the ` . ' and ` . . ' entries are checked to make sure they exist , and that the inode number for the ` . ' entry matches the current directory . ( the inode number for the ` . . ' entry is not checked until pass 3 . )

pass 2 also caches information concerning the parent directory in which each directory is linked . ( if a directory is referenced by more than one directory , the second reference of the directory is treated as an illegal hard link , and it is removed ) .

needs to perform is complete . information required by passes 3 , 4 and 5 are cached in memory ; hence , the remaining passes of

traces the path of each directory back to the root , using information that was cached during pass 2 . at this time , the ` . . ' entry for each directory is also checked to make sure it is valid . any directories which can not be traced back to the root are linked to the

checks the reference counts for all inodes , by iterating over all the inodes and comparing the link counts ( which were cached in pass 1 ) against internal counters computed during passes 2 and 3 . any undeleted files with a zero link count is also linked to the

checks the validity of the filesystem summary information . it compares the block and inode bitmaps which were constructed during the previous passes against the actual bitmaps on the filesystem , and corrects the on - disk copies if necessary .

is a powerful program which can be used to examine and change the state of a filesystem . basically , it provides an interactive interface to the ext2fs library : commands typed by the user are translated into calls to the library routines .

. unfortunately , this program can be dangerous if it is used by people who do not know what they are doing ; it is very easy to destroy a filesystem with this tool . for this reason ,

opens filesytems for read - only access by default . the user must explicitly specify the

we have run benchmarks to measure filesystem performances . benchmarks have been made on a middle - end pc , based on a i486dx2 processor , using 16 mb of memory and two 420 mb ide disks . the tests were run on ext2 fs and xia fs ( linux 1 . 1 . 62 ) and on the bsd fast filesystem in asynchronous and synchronous mode ( freebsd 2 . 0 alpha - - based on the 4 . 4bsd lite distribution ) .

we have run two different benchmarks . the bonnie benchmark tests i / o speed on a big file - - the file size was set to 60 mb during the tests . it writes data to the file using character based i / o , rewrites the contents of the whole file , writes data using block based i / o , reads the file using character i / o and block i / o , and seeks into the file . the andrew benchmark was developed at carneggie mellon university and has been used at the university of berkeley to benchmark bsd ffs and lfs . it runs in five phases : it creates a directory hierarchy , makes a copy of the data , recursively examine the status of every file , examine every byte of every file , and compile several of the files .

the results are very good in block oriented i / o : ext2 fs outperforms other filesystems . this is clearly a benefit of the optimizations included in the allocation routines . writes are fast because data is written in cluster mode . reads are fast because contiguous blocks have been allocated to the file . thus there is no head seek between two reads and the readahead optimizations can be fully used .

on the other hand , performance is better in the freebsd operating system in character oriented i / o . this is probably due to the fact that freebsd and linux do not use the same stdio routines in their respective c libraries . it seems that freebsd has a more optimized character i / o library and its performance is better .

the results of the two first passes show that linux benefits from its asynchronous metadata i / o . in passes 1 and 2 , directories and files are created and bsd synchronously writes inodes and directory entries . there is an anomaly , though : even in asynchronous mode , the performance under bsd is poor . we suspect that the asynchronous support under freebsd is not fully implemented .

in pass 3 , the linux and bsd times are very similar . this is a big progress against the same benchmark run six months ago . while bsd used to outperform linux by a factor of 3 in this test , the addition of a file name cache in the vfs has fixed this performance problem .

in passes 4 and 5 , linux is faster than freebsd mainly because it uses an unified buffer cache management . the buffer cache space can grow when needed and use more memory than the one in freebsd , which uses a fixed size buffer cache . comparison of the ext2fs and xiafs results shows that the optimizations included in ext2fs are really useful : the performance gain between ext2fs and xiafs is around 5 - 10 % .

the second extended file system is probably the most widely used filesystem in the linux community . it provides standard unix file semantics and advanced features . moreover , thanks to the optimizations included in the kernel code , it is robust and offers excellent performance .

since ext2fs has been designed with evolution in mind , it contains hooks that can be used to add new features . some people are working on extensions to the current filesystem : access control lists conforming to the posix semantics

ext2fs was first developed and integrated in the linux kernel and is now actively being ported to other operating systems . an ext2fs server running on top of the gnu hurd has been implemented . people are also working on an ext2fs port in the lites server , running on top of the mach microkernel

, and in the vsta operating system . last , but not least , ext2fs is an important part of the masix operating system

the ext2fs kernel code and tools have been written mostly by the authors of this paper . some other people have also contributed to the development of ext2fs either by suggesting new features or by sending patches . we want to thank these contributors for their help .

m . accetta , r . baron , w . bolosky , d . golub , r . rashid , a . tevanian , and m . young . mach : a new kernel foundation for unix development . in

e . bina and p . emrath . a faster fsck for bsd unix . in

r . card , e . commelin , s . dayras , and f . mével . the masix multi - server operating system . in

s . kleiman . vnodes : an architecture for multiple file system types in sun unix . in

m . mckusick , w . joy , s . leffler , and r . fabry . a fast file system for unix .

m . seltzer , k . bostic , m . mckusick , and c . staelin . an implementation of a log - structured file system for unix . in

thanks to michael johnson for htmlizing it ( originally for use in the kernel hacker ' s guide ) .

the ext2 filesystem was designed with the goal of expandability while maintaining compatibility . this paper describes ways in which advanced filesystem features can be added to the ext2 filesystem while retaining forwards and backwards compatibility as much as possible . some of the filesystem extensions that are discussed include directory indexing , online resizing , an expanded inode , extended attributes and access control lists support , extensible inode tables , extent maps , and preallocation .

] ( also known as ext2 ) was first introduced into the linux kernel in january , 1993 . at the time , it was a significant improvement over the previous filesystems used in the 0 . 97 and earlier kernels , the minix and the ` ` extended ' ' or ( ext ) filesystem . fundamentally , the design of the ext2 filesystem is very similar to that of the bsd fast filesystem [

which are essentially identical to the ffs ' s cylinder group ; each block group contains a copy of the superblock , allocation bitmaps , part of a fixed , statically allocated inode table , and data blocks which can be allocated for directories or files . like most classic unix filesystems , ext2 / 3 uses direct , indirect , double indirect , and triple indirection blocks to map logical block numbers to physical block numbers . ext2 ' s directory format is also essentially identical to traditional unix filesystems in that a simple linked list data structure is used to store directory entries .

over the years , various improvements have been added to the ext2 filesystem . this has been facilitated by a number of superblock fields that were added to the ext2 filesystem just before linux 2 . 0 was released . the most important of these fields , the compatibility bitmaps , enable new features to be added to the filesystem safely . there are three such compatibility bitmaps : read - write , read - only , and incompat . a kernel will mount a filesystem that has a bit in the read - write compatibility bitmask that it doesn ' t understand . however , an unknown bit in the read - only compatibility bitmap cause the kernel to only be willing to mount the filesystem read - only , and the kernel will refuse to mount in any way a filesystem with an unknown bit in the incompat bitmask . these bitmaps have allowed the ext2 filesystem to evolve in very clean fashion .

today , more developers than ever have expressed interest in working on the ext2 / 3 filesystem , and have wanted to add or integrate various new exciting features . some of these features include : preallocation , journaling , extended attributes and access control lists , on - line resizing , tail - merging , and compression . some of these features have yet to be merged into the mainline ext2 code base , or are only available in prototype form . in the case of the journaling support , although filesystems with journaling support are fully backwards compatible with non - journalled ext2 filesystems , the implementation required enough changes that the resulting filesystem has been named

the goal of this paper is to discuss how these features might be added to the filesystem in a coordinated fashion . many of these new features are expected of modern filesystems ; the challenge is to add them while maintaining ext2 / 3 ' s advantages of a relatively small and simple code base , robustness in the face of i / o errors , and high levels of forwards and backwards compatibility .

we will discuss a number of extensions to the ext2 / 3 filesystem which will likely be implemented in the near future . for the most part , these extensions are independent of each other , and can be implemented in any order , although some extensions have synergistic effects . for example , two new features that will be described below , extent maps and persistent preallocation , are far more effective when used in combination with each other .

] . this replaces the linear directory search algorithm currently in use with traditional ext2 filesystems , and significantly improves performance for very large directories ( thousands of files in a single directory ) .

the interior , or index , nodes in the tree are formatted to look like deleted directory entries , and the leaf nodes use the same format as existing ext2 directory blocks . as a result , read - only backwards compatibility is trivially achieved . furthermore , starting in the linux 2 . 2 kernel , whenever a directory is modified , the

) is cleared . this allows us to guarantee read / write compatibility with linux 2 . 2 kernels , since the filesystem can detect that the internal indexing nodes are probably no longer consistent , and thus should be ignored until they can be reconstructed ( via the

daniel phillip ' s directory indexing code is currently available as a set of patches versus the 2 . 4 ext2 code base . as of this writing , the patches still need to be merged with the ext3 journaling code base . in addition , there are plans to select a better hash function that has better distribution characteristics for filenames commonly found in workloads such as mail queue directories . there are also plans to add hinting information in the interior nodes of the tree to indicate that a particular leaf node is nearly empty and that its contents could be merged with an adjacent leaf node .

andreas dilger has implemented patches to the ext2 filesystem that support dynamically increasing the size of the filesystem while the filesystem is on - line . before logical volume managers ( lvms ) became available for linux , off - line resizing tools such as

first , were sufficient for most users ' needs . however , with the advent of lvm systems that allow block devices to be dynamically grown , it is much more important filesystems to be able to grow and take advantage of new storage space which has been made available by the lvm subsystem without needing to unmount the filesystem first . indeed , administrators of enterprise - class systems take such capabilities for granted . ( dynamically shrinking mounted filesystems is a much more difficult task , and most filesystems do not offer this functionality . for ext2 / 3 filesystems , filesystems can be shrunk using the off - line resizing tool

a disadvantage of the current ext2 resizing patches is that they require that the filesystem be prepared before the filesystem can be resized on - line . this preparation process , which must be done with the filesystem unmounted , finds the inodes using the blocks immediately following the block group descriptors , and relocates these blocks so they can be reserved for the resizing process . these blocks must be reserved since the current layout of the ext2 superblock and block group descriptors require an additional block group descriptor block for each 256mb , 2gb , or 16gb of disk space for filesystems with 1kb , 2kb , and 4kb blocksizes , respectively . although the requirement for an off - line preparation step is quite inconvenient , this scheme does have the advantage that the filesystem format remains unmodified , so it is fully compatible with kernels that do not support on - line resizing . still , if the system administrator knows in advance how much a filesystem may need to be grown , reserving blocks for use by the block group descriptors may be a workable solution .

requiring advance preparation of the filesystem can be obviated if we are willing to let the filesystem become incompatible with older kernels after it has been extended . given that many 2 . 0 and 2 . 2 kernels do not support lvm devices ( and so would be unable to read a filesystem stored on an lvm anyway ) , this may be acceptable . the change in the filesystem format replaces the current scheme where the superblock is followed by a variable - length set of block group descriptors . instead , the superblock and a

. a meta - block group is a collection of block groups which can be described by a single block group descriptor block . since the size of the block group descriptor structure is 32 bytes , a meta - block group contains 32 block groups for filesystems with a 1kb block size , and 128 block groups for filesystems with a 4kb blocksize . filesystems can either be created using this new block group descriptor layout , or existing filesystems can be resized on - line , and a new field in the superblock will indicate the first block group using this new layout .

this new scheme is much more efficient , while retaining enough redundancy in case of hardware failures . most importantly , it allows new block groups to be added to the filesystem without needing to change block group descriptors in the earlier parts of the disk . hence , it should be very simple to write an ext2 / 3 filesystem extension using this design that provides on - line resizing capabilities .

the size of the on - disk inode in the ext2 / 3 filesystem has been 128 bytes long during its entire lifetime . although we have been very careful about packing as much information as possible into the inode , we are finally getting to the point where there simply is not enough room for all of the extensions that people would like to add to the ext2 / 3 filesystem .

fortunately , just before the release of linux 2 . 0 , most of the work to allow for an expanded inode was added . as part of the changes to version 1 of the ext2 superblock , the size of the inode in the filesystem was added as a parameter in the superblock . the only restriction on the size of inode is that it must evenly divide the filesystem blocksize . unfortunately , some safety - checking code which aborted the filesystem from being mounted if the inode size was not 128 bytes was never removed from the kernel . hence , in order to support larger inodes , a small patch will have to made to the 2 . 0 , 2 . 2 , and 2 . 4 kernels . fortunately the change is simple enough that it should be relatively easy to get the change accepted into production kernels .

one of the most important features that requires additional space in the inode is the addition of sub - second resolution timestamps . this is needed because given today ' s very fast computers , storing file modification times with only second granularity is not sufficient for programs like

command will not be able to determine whether or not the library needs to be updated . )

, which limits the number of subdirectories that can be created in a single directory . the actual limit of 32 , 000 is smaller than what is possible with an unsigned 16 - bit field , but even if the kernel were changed to allow 65 , 535 subdirectories , this would be too small for some users or applications .

in addition , extra inode space can also enable support 64 - bit block numbers . currently , using 4kb blocks , the largest filesystem that ext2 can support is 16tb . although this is larger than any commonly available individual disks , there certainly are raid systems that export block devices which are larger than this size .

] ( mac ) or audit labels . the nsa se ( security - enhanced ) linux [

] implementation requires a single 32 - bit field for both purposes ; other schemes may require two separate 32 - bit fields to encode mac and audit label .

in order to maximize backwards compatibility , the inode will be expanded without changing the layout of the first 128 bytes . this allows for full backwards compatibility if the the new features in use are themselves backwards compatible - - for example , sub - second resolution timestamps .

doubling the inode size from 128 bytes to 256 bytes gives us room for 32 additional 32 - bit fields , which is a lot of extra flexibility for new features . however , the 32 new fields can be very quickly consumed by designers proposing filesystem extensions . for example , adding support for 64 - bit block pointers will consume almost half of the new fields . hence , allocation of these new inode fields will have to be very carefully done . new filesystem features which do not have general applicability , or which require a large amount of space , will likely