Data Storage for VDI – Part 9 – Capex and SAN vs DAS
I’d intended writing about Megacaches in both the previous post, as well as this one, but interesting things keep popping up that need to be dealt with first. This time it’s an article at information week With VDI, Local Disk Is A Thing Of The Past. In it Elias Khnaser outlines the same argument that I was going to make after I’d dealt with the technical details of how NetApp optimises VDI deployments.
I still plan to expand on this with posts on Megacaches, single instancing technologies, and broker integration, but Elias’ post was so well done that I thought it deserved some immediate attention.
If you havent done so already, check out the article before you read more here, because the only point I want to make in this uncharacteristically small post is the following
The capital expenditure for storage in a VDI deployment based on NetApp is lower than one based on direct attached storage.
This is based on the following
Solution 1: VDI Using Local Storage – Cost
Solution 2 : VDI Using HDS Midrange SAN – Cost
$860,800, with array costs of approx $400,000
Solution 3 : VDI Using FAS 2040 – Cost
860,000 – 400,000 + (2000 * $50) = $560,000
You save $54,000 (about 10% overall) compared to DAS and still get the benefits of shared storage. That’s $56,000 you can spend on more advanced broker software or possibly a trip to the Bahamas.
Now if you’re wondering where I got my figures from, I did the same sizing exercise I did in Part 7 of this post but using 12 IOPS per user and using 33:63 R:W ratio. I then came up with a configuration and asked one of my colleagues for a street price. The figure came out to around $US50/desktop user for an NFS deployment, which is inline with what NetApp has been saying for about our costs for VDI deployments for some time now.
Even factoring in things like professional services, additional network infrastructure, training etc, you’d still be better off from a up-front expenditure point of view using NetApp than you would with internal disks.
Given the additional OpEx benefits, I wonder why anyone would even consider using DAS, or even for that matter another vendors SAN.