Comparing Traditional Datacenters to Private Clouds
I received a flood of e-mails from my last blog comparing enterprise datacenters to private clouds. I also received queries about the differences between a highly virtualized enterprise datacenter and a private cloud. So, before I continue, let me step back and explain the differences.
The traditional enterprise datacenter of today is built by adding more compute, more storage and more networking. If you take a closer look at how we acquire and build these resources, you will notice that we buy these components individually for the most part and then put them together. We also tend to scale them out separately: You need more storage, you add more disk; you need more compute, you buy more servers; etc. That process is slow and is very labor intensive, but we have done for so many years that it has become part of our DNA, and we don't notice it anymore.
In a cloud environment acquiring resources is different. We acquire them in PODs or containers of compute, network and storage that we simply add to our resource pool in order to grow it and increase its capabilities. Physical resources are added and then logically carved out using software. You can see how the approaches differ especially when you consider that these PODs are pre-built and pre-tested, you roll them in and you connect them and then use your orchestration tools to integrate the newly added resources. The cloud approach allows your private cloud to be elastic, not in the traditional public cloud model because there is no way for an internal private cloud to scale to any of the public could offerings, but instead it is elastic in that you can very easily add resources and increase capabilities.
It is also important to note that the traditional datacenter is made up of primarily client-server type applications. These applications have a dependency on a single operating system, and this is opposite to how cloud applications are built around service-oriented architectures. In order for us to have a true cloud platform, we would have to rewrite these applications based on SOA standards, which is not going to happen for the majority of our enterprise applications. As a result, the closest we can get to a cloud platform is to automate and orchestrate our environment, develop a set of standards and processes which would allow us to scale faster.
Today, we still manually provision VMs. The problem is, organizations are having to deal with increasing number of virtual machines. The fix is to hire more admins and while that is great for the economy, that just does not scale, so we have to learn to build standards and automate and orchestrate in order to get away from manual, repeated tasks.
Another significant difference between an enterprise datacenter and an internal private cloud is that with a traditional datacenter the business has complete reliance on IT for acquiring resources -- there is no self-service approach, no chargeback or showback model, no services approach. Basically, there is an IT “waiter” that takes down the requirements, manually builds a VM to meet these requirements and hands it over to the application owners.
In an internal private cloud model, we have a self-service portal with predefined virtual machine offerings that application owners can consume and will have to make their applications work within a predefined framework.
We can also take it one step further by creating the services concept. A service is a collection of VMs that are managed as a single entity; VMware vSphere and Citrix XnServer call this concept vApps. In retrospect, when you apply this to your cloud design, you end up offering a service that your users can consume or provision.
Finally, when you build an internal private cloud your infrastructure is also very highly automated and orchestrated. As a result, your traditional rack-stack-install-and-configure approach changes in exchange for stateless servers that PXE boot and deploy the correct image depending on the IP address range they are connecting from.
Please keep the e-mails coming. Better yet, leave a comment so that we can engage the rest of the readers.
Posted by Elias Khnaser on 02/06/2012 at 12:49 PM