Is that Cirrus or Cumulonimbus?
I have never been a fan of the phrase ‘cloud computing’, it is a buzz word designed to dumb down a technology for people rather than explaining the correct name which is Platform as a Service (PaaS). My go to answer when people would ask “What is Cloud” was “It’s just somebody else’s computer”, but then we termed the phrase ‘private cloud’ which has ruined that! To exacerbate this problem, we now have even more versions with the use of terms like hybrid cloud and multi-cloud.
To explain the differences between these two and what they mean we need to first explain what the ‘cloud’ is. Simply put, it is the next step up from hosting. As the demand for resilient infrastructure became necessary for server infrastructure, the use of external datacentre services grew. This was termed as co-location (Co-Lo) and meant that the responsibility for providing power, cooling, physical security and some networking infrastructure was now a service. The companies that owned these Datacentres (DCs) then realised that they could extend their services by filling cabinets with their own servers and renting these out. The company renting them was responsible for managing the Operating System (OS) or the virtualisation layer and the VMs running on the servers. This service became known as Hosting. It was more flexible than Co-Lo and was the first step to changing server infrastructure from a CAPEX cost to an OPEX cost. The draw back to it, however, was the storage side and how to incorporate that easily.
Coining a Phrase
This led to the first named ‘as a Service’ offering, infrastructure. This is a virtual infrastructure run and managed by a 3rd party that will include tiered performance storage offerings. Clients will pick standardised VM templates to be deployed from a catalogue which they will then be responsible for managing and configuring the OS on. Hosting in other words, but at the virtualisation layer.
What if you didn’t have the skillset in-house to set-up and manage the OS layer, or indeed a large database? This is the next level up and is known as Platform-as-a-Service. All the client now has to worry about is the application they want to install, and the catalogue now offers not only VM sizes, but database connections and .NET or J2EE versions. All the patching and security of the OS layer is now the responsibility of the provider, who is probably offering their services from a different IaaS provider.
Finally, we have SaaS (Software-as-a-Service). All the customer needs to worry about here is the data. Examples of this are Office 365, Google G Suite and Salesforce CRM. The customer has no control over versions, but equally has no concerns over patching and security. They just pay for the application to be provided. Packages will normally include backup or resilient storage capability, but with this comes the concern as to where data is being stored as providers will be utilising the cheapest IaaS or hosting they can use.
When does a calf become a bull?
The question left now is when does On-Premises, Co-Lo or Hosted stop being ‘private infrastructure’ and become ‘private cloud’? VMware’s answer is when you add functionality such as automation and operations management – VMware vROps (vRealize Operations) and vRA (VMware vRealize Automation) or CMP (Cloud Management Platform) as it was termed. The problem here is that public cloud providers have billing capabilities and tenancy management so is it truly ‘Cloud’ or still just private infrastructure?
Anyway, this is the ‘Cloud’. It has many flavours, not only in the levels of service and responsibility, but in the underlying platform and this can be a problem for the IaaS and PaaS layer. An obvious example of the differences is between AWS and Azure clouds. Azure is based on the Microsoft (MS) operating platform and AWS is based on Linux. To swap between the two is not an easy task and since there are inherent differences in the way you configure VMs for use in a public cloud environment to your own more flexible environment (Private Cloud) – this is 