31301873
Parity Striping of Disk Arrays: Low-Cost Reliable Storage with Acceptable Throughput
An analysis of mirrored discs and of RAID5 shows that mirrors have considerably better throughput, measured as requests/second on random requests of arbitrary size (up to 1MB). Mirrors have comparable or better response time for requests of reasonable size (less than 100KB). But mirrors have a 100% storage penalty: storing the data twice. Parity striping is a data layout that stripes the parity across the discs, but does not stripe the data. Parity striping has throughput almost as good as mirrors, and has cost/GB comparable to RAID5 designs -combing the advantages of both for high-traffic disc resident data. Parity striping has additional fault containment and software benefits as well. Parity striping sacrifices the high data transfer rates of RAID designs for high throughput. It is argued that response time and throughput are preferable performance metrics. Outline Introduction Why Striping and RAID Are Inappropriate for OLTP Systems Parity Striping: Cheap Reliable Storage Plus High Throughput An Analysis of Mirrors, RAID5, and Parity Stripe Performance Mirrored Discs Parity Stripe Discs RAID5 Discs Applying the Analysis to a 10+2 array The Read-Only Case The Write-Only Case Analyzing a High-Performance Disc Other Benefits of Parity Striping Summary Acknowledgments References Appendix: Spreadsheets Corresponding to the Graphs
208948503
Third-Generation Database System Manifesto - The Committee for Advanced DBMS Function.
215936012
Evolution of Data Management
Society has made great strides in capturing, storing, managing, analyzing, and visualizing data. These tasks are generically called data management, and this article sketches its evolution through ...
3204824
Designing a multi-petabyte database for LSST
The 3.2 giga-pixel LSST camera will produce approximately half a petabyte of archive images every month. These data need to be reduced in under a minute to produce real-time transient alerts, and then added to the cumulative catalog for further analysis. The catalog is expected to grow about three hundred terabytes per year. The data volume, the real-time transient alerting requirements of the LSST, and its spatio-temporal aspects require innovative techniques to build an efficient data access system at reasonable cost. As currently envisioned, the system will rely on a database for catalogs and metadata. Several database systems are being evaluated to understand how they perform at these data rates, data volumes, and access patterns. This paper describes the LSST requirements, the challenges they impose, the data access philosophy, results to date from evaluating available database technologies against LSST requirements, and the proposed database architecture to meet the data challenges.
33551622
The Theory of Sequential Relations
Suppose that one has some system with inputs drawn from a set Z* which produces outputs in some set Lx*. The system is assumed to have sonm state set S. Suppose that all possible experiments are run on the system ill the sense that we can tabulate a relation R of all inpuVoutput pairs which the system can produce. (We will vary the starting state.) A problem of some importance in systems theory (Zadeh and Desoer, 1963) is to synthesize a system which has as its relation R where R has been "given" in advance. In this paper, we study sequential relations which are the relations which arise in this manner when the system is a finite sequential machine. Our main results include synthesis procedures for constructing the sequential machine when the relation is "reasonably given." Also several characterizations of sequential relations are given as well as connections with other families of relations studied in automata theory. This study was stimulated by a lecture given by Professor 5i. A. Aizermann in July 1964 at the University of California, Berkeley. Professor Aizermann described a method for the synthesis of sequential machines by a "question-answer" procedure. Since the technical details of the method were omitted, we derived a method which satisfied the general characteristics mentioncd by Professor Aizernmnn. Recently, the original algorithm has become available (see Tal, 1964). I t turns out that the two methods have very little in common. Our method is • 7, presented as an appendix to this ]oa~dr. , Our method synthesizes a sequential function f by constructing the minimal sequential machine which computes f; this machine has a dis-
40830661
Greetings from a Filesystem User
10364748
Why Do Computers Stop and What Can Be Done About It?
An analysis of the failure statistics of a commercially available fault-tolerant system shows that administration and software are the major contributors to failure. Various approaches to software fault-tolerance are then discussed -- notably process-pairs, transactions and reliable storage. It is pointed out that faults in production software are often soft (transient) and that a transaction mechanism combined with persistent processpairs provides fault-tolerant execution -- the key to software fault-tolerance.
41817845
Why TP-Lite will Dominate the TP Market
13482322
Triumphs, Sins, and Challenges of Database Benchmarking
10432009
Increasing the Effectiveness of OS Research
35790813
Mobile technologies for the world's children
In this panel, academic, non-profit, and industry professionals will discuss their global perspectives on mobile technologies for the world's children. Panelists will explore such issues concerning children's access to mobile devices, the decreasing age that children have access to these technologies, mobile innovations for learning, and challenges/opportunities in diverse countries. This interactive session will begin with each panelist giving a short summary of their work-to-date with children and various mobile applications. Then the panelists will be asked questions by children from different countries via pre-recorded video. Audience members will be invited to offer their thoughts and comments as well as the panelists during the video question period. Audience members will also be able to ask further questions throughout the panel discussion.