Everyday Virtualization

Blog archive

Thin Provisioning: Under Control

Last week, I was at TechMentor in Orlando and a very interesting point was brought up in the virtualization track. For thin provisioning, who do you want doing it? Should the storage system or the virtualization platform administer this disk-space-saving feature? The recommendation was to use the storage system to provide thin provisioning on the LUN if supported. As a fan of virtualization in general and with vSphere's thin provisioning of VMDK files being one of my most anticipated features, I stopped and thought a bit about this recommendation. Then this sounded familiar to discussions of having software RAID or hardware RAID: We clearly want hardware controllers administering RAID arrays.

While it is not quantified, there is overhead to having a thin-provisioned disk with vSphere. The storage array may have overhead for a thin-provisioned LUN as well. I mentioned earlier how thin-provisioning monitoring is important with vSphere, but should we just go the hardware route? Of course this is assuming that the storage system supports thin-provisioning for ESX and ESXi installations.

What is your preference on this practice? I am inclined to determine that a hardware-administered (storage system) solution is going to be cleaner. Share your thoughts below or shoot me a message with your opinion.

Posted by Rick Vanover on 06/30/2009 at 1:38 PM


Reader Comments:

Tue, Jul 7, 2009 Rick Vanover Grand Rapids, MI

Stephen: Good to know. Definitely want to have the storage system do it if possible.

Rock on! Thanks for checking in here.

Tue, Jul 7, 2009 Stephen Sanford, FL

I had always wondered how a SAN could be intelligent enough to know that a thick .vmdk was only really filled with a percentage of actual data. I asked you about this at TechMentor and you said you believed our Compellent SAN was VMFS aware. I checked our VMFS volumes on our Compellent SAN and sure enough, the actual data consumed is about 55-60% of what is provisioned. So it looks like the new implementation of thin provisioning in vSphere won't be necessary for us.

Add Your Comment:

Your Name:(optional)
Your Email:(optional)
Your Location:(optional)
Comment:
Please type the letters/numbers you see above