“I don’t get the private cloud”, “We’re already virtual so we have a cloud”

Simon May

Sometimes I think them a strange reaction from technology professionals but really they are both based around a simple misunderstanding; what a cloud and specifically what a private cloud is. The answer though is actually pretty clear cut if you look for a definition, we prefer the NIST definition, since it was independently created.

A cloud is:

Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model promotes availability and is composed of five essential characteristics, three service models, and four deployment models.

A private cloud is:

The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on premise or off premise.

So lets take a look at the second of the two statements in the title given the context of these two definitions (if this seems a bit academic that's going to go away quickly). Virtualisation is a stepping stone on the path to the cloud because the cloud needs us to have a level of abstraction of separation from the workload or service we provide to the *stuff* that's providing it. I intentionally use the term stuff because it's vague and non-committal. The stuff can be hardware, that's the virtualisation scenario that we're most used to taking a server running an application and virtualising the server and application together because it's a pretty simple thing to do. Virtualisation in the sense of a the cloud though can be at a higher level, taking the application or the workload that's being done and virtualising that removing the specific requirements of the operating system underneath. If you're familiar with the terms of IaaS and PaaS then you're probably seeing some parallels, but wait.

All we've done is virtualise something, it's not at this point doing anything to take advantage of other parts of the above definition. Sure it's using a shared pool of resource but can you rapidly provision and release that virtual server or application? Probably not if the infrastructure hasn't been built to automatically know about other servers popping up and if it's not aware of those other servers popping up how do we make them work perfectly together? Manual intervention? It's not sounding like "minimal management effort".

The essential next thing required around a virtualised infrastructure to enable it to become a cloud is management software that provides intelligence. It's time to introduce some new vocabulary to this conversation: fabric. The virtualised *stuff* is the fabric. It's all the processors, disks, memory, SANs, Switches, racks, power blocks all the stuff that the OS and the application run on. The management software becomes the fabric controller, making decisions about where resource is needed. This fabric controller or management software isn't the final step though, it's not easy enough yet to be "minimal management".

The final step comes from adding a mechanism that allows the end consumers of the services to utilise them without having any appreciation for the stuff that the fabric is managing. We call this a self service portal, pretty self explanatory you'd think. What that self service portal does is abstract the complexity for the consumer of the service but there's still complexity there and someone, someone with understanding, needs to set things up in a way that they can be consumed. In the case of Windows Azure, Office 365 or Windows Intune that someone is a clever kid inside Microsoft, in the case of the private cloud it's the IT Professional.

Oh but we've not talked about private cloud yet. What's a Private cloud? Well from the second definition it's one that's operated and may be managed by the organisation that uses it and that definition is not mutually exclusive from the above. A private cloud must be highly virtualised, self managing, consumer servicing if it's not you have either a highly virtualised infrastructure or a highly virtualised and well managed infrastructure but not a cloud. And no cloud is not just a term to put on something, there's meaning behind it.

From Microsoft this means having Hyper-V, System Center and a Self Service Portal such as Self Service Portal 2.0

Get your questions answered on Twitter If you're still confused by it all then I have a recommendation, tweet @ASKTechNetUK with a question and the hash tag #cloudpro and on Friday 15th April at 2pm we'll answer your question along with lots of others we've already received. We, of course, are real people, @simonster, @deepfat and Steve "Planky" Plank.

Get your questions answered by text and blog However if you don't like the twitter thing, you can text your question to 80809 followed by "cloudpro" and we'll answer it and you'll be able to see the answers on this blog after Friday 15th.

Get your questions answered in person Finally, if you prefer the in person stuff we still have capacity (but not much) for TechDays 2011 and we'll be talking about both the public and private cloud.