Funny I was about to ask the forum if anyone is using the UNMAP command
We have a P7400 and ESXi5.1u1 and could not understand why space reclamation was not happening till I read this:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2014849As far as I can see VMware have disabled the command 'period' the impact on the backend storage was to unpredictable its now up to you the customer to enable it on all your hosts.
The question is how is it handled on the 3PAR, our test seems to suggest it's not a real-time process as the space does not reflect immediately once we delete a VM, also we ran test and could not really see an impact, but then again the unit was not in production at the time. It's now in production and we thought it best to ask around before enabling it.
So... has anyone out there enable it? (advanced/VMFS3.EnableBlockDelete=1)
PS I recently read that 'another' storage vender who's name I will not mention lest I soil this list
has picked up an issue with the VMware UNMAP code that has issues when reclaiming more that 2TB BUT I think they are confused and have mixed UNMAP with a manual reclaim (vmkfstools) as I understood that UNMAP run in the background on a storage system:
http://cormachogan.com/2013/05/14/heads-up-unmap-considerations-when-reclaiming-more-than-2tb/