Virtualization: Lessons Learnt

If you were thinking I am going to give you some great tips about virtualization, let me make it clear that the title of this post must be taken literally and not figuratively. I attended a VMWare 4 day course at GT Enterprises, Bangalore and this post is regarding what I really learnt in the course. The course was conducted well and the trainer was good.

I did know a bit about VMware, having installed the workstation and server versions earlier and working with them. I did not have an idea about VMWare ESX / ESXi and the course was a good place to start. Though the course is more aimed at the server / storage admin (it is called ‘Install, Configure and Manage’) and I was looking at it from an engineering perspective, it was nevertheless a good course to attend. Once you attend the course, you get a much more clearer understanding of what VMware is all about, how useful server virtualization is to the enterprise and the various innovations being made by VMware to improve the product.

One of the things I liked a lot was the focus on management. vCentre is a nice piece of work which allows you to manage things from a single place and this is definitely something a large enterprise would require. Otherwise it will be a nightmare managing so many virtual machines individually. Same goes for the distributed vswitch available in VMware. Another nice concept. We worked on only the Distributed vSwitch of VMware and not on the Cisco virtual switch. It would have been nice had I got an idea of how that is configured but I guess you need to attend a Cisco training for that. Asking it in VMware training would be too much.

vMotion was another feature which impressed me. The ease with which you can move a VM from one physical server to another is incredible. Ofcourse certain pre-requisites need to be met. vCenter is smart enough to tell you which VMs can move to which servers. Similarly Storage vMotion was also quite easy to use. Also got  a better idea about Storage for VMware, High Availability, Clustering etc.

Some of the features have their own limitations and going by the new release it is clear that VMware is fully aware of the limitations and is working on them. The vSphere 4.1 released very recently had some nice features which are primarily aimed at improving the Storage I/O efficiency. Two important aspects related to storage were:

vStorage API for Array Integration (VAAI)

Storage I/O control (SIOC)

VAAI provides API for Storage Array makers so that some of the storage operations like Full Copy can be performed at the array level rather than involving the server resources. SIOC is a way in which to ensure the right job gets the right priority as far as storage is concerned. Here are links to two articles which cover these two aspects:

VAAI article by Mark Farley (aka 3parfarley)

SIOC article at technodrone (You will see this link in Mark’s article as well)  In order o understand SIOC you need to know something about what shares are and how they are allocated in VMware. Even if you are not aware, you will still get a general idea of how the concept works by reading the article.

The vSphere 4.1 release will certainly help in faster and fairer storage access.

This training I took is mandatory if you are planning to take up a VCP certification. If you don’t have such plans and want to know more about VMware vSphere, you can check out Scott Lowe’s book, “Mastering VMware vSphere 4”. (Scott is a well respected blogger in the virtualization world. He was an independent blogger who later joined EMC. His blog at still provides a lot of information which is neutral (that is, not plugging for EMC) ) This is a well written book and covers a lot of ground. I would suggest this book even to those who have attended the course, since Scott provides lot of insights into many of the features and gives a good background on each topic. I am sure it will be of immense help to those taking up the VCP exam.(I have recently seen another book in the book stores which deals with vSphere 4 but I haven’t been able to read it yet.) Scott’s book is published by Wiley India and costs Rs.599/- (Actual cost would depend on how much discount you would get. I generally get anywhere between 17 to 25% discount at Book Paradise, Jayanagar, Bangalore. The quantum of discount depends on the number of books you buy.)

Before I end, let me also note that I recently gave a talk titled, “Server and Storage Virtualization: Their relevance to the Cloud” at Mindtree Consulting. This was an invited talk as a part of their internal initiative. The talk was well attended, the participants were interactive and the feedback was positive. The arrangements were well done. I enjoyed the session and the interaction.  Thanks to Rama Narayanaswamy, VP at Mindtree Consulting, who made this happen.