Impact of Server Virtualization on Storage

"Customers are realizing the ability to virtualize on a single machine is "just a tiny piece of what virtualization can do for you," Greene said. To achieve real reductions in capex and op-ex, companies need virtualization infrastructure: all the management bells and whistles controlling a data center full of servers, she said."

The above comment was made by Diane Green in an article posted at the TheStreet.com a few days ago. Diane's right on the money.

A lot of folks don't realize that while server virtualization technologies deliver tangible results in increasing physical server utilization rates, at the same time they significantly impact storage utilization rates.

Lets think about what's happening when we virtualize servers. At a minimum, we move 15-20GB of redundant OS data into shared storage. If you multiply this number times the consolidation factor, it gets expensive real fast in terms of the capacity required to host these duplicate images. That coupled with the fact that administrators tend to ask for greater up-front allocation of storage than they would typically need, creates some serious low storage capacity utilization issues. And if you think virtualizing 500 servers creates storage capacity utilization issues, how about virtualizing 5000 desktops?

This is like stealing from Peter to pay Paul, as at least part of the savings realized from the physical server consolidation will now be spent on storage.

So how do you address these issues? In order to do so, you would need to consider storage virtualization as part of your design and deployment and take advantage of data deduplication, thin provisioning, and space efficient cloning technologies.

In fact, these technologies lower the cost threshold for enterprises to start fully utilizing them as there's no tradeoff between the cost versus the benefits they provide.

How about performance?

Server virtualization is notorious for creating high levels of small block random I/O. This high level of randomness can translate to array cache misses which means that performance to and from disk becomes important. That also means that arrays that stripe across a large number of spindles are better equipped to handle this potential issue than arrays that have continued to rely on the creation and usage of small raid groups comprised of 5-8 drives.

How about Data protection?

What's the cost of a dual disk failure in a physical server tied to one application versus the cost of the same failure in a virtual infrastructure tied to multiple apps? How many apps do you have to recover now? So the need for RAID-6 solutions is even more pronounced. And not just RAID 6 but high-performing RAID-6.  

So to Diane's point, failure to consider storage virtualization as part of your server virtualization strategy will only shift costs from the server to the storage.

Comments

[Dan Pancamo]

you should stay blogspot, Your blogs will be more creditable and less bias...

[Nick Triantos]

Thanks for the advice Dan. You mean appear less biased :-)

The truth of the matter is the guidelines applied on this corporate sponsored blog are more relaxed than you can imagine, and that's why I decided to hop on. In fact, anyone who applies common sense is eligible.

Furthermore, the blog maybe sponsored by NetApp, but, I want to make this as clear as it was made to me, that the views expressed do not necessarily have the company's sponsorship.

Cheers

Another reason I jumped on, is because I have found it much easier during testing to post videos/demos here vs blogspot. The last time I tried several times to upload a video on blogspot it took 8 1/2 hrs and it didn't complete.