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Doing Reclaim on Thin Devices
I have been noticing in Unisphere for VMAX that the allocated space on TDEV are not correlating to that in VMware. For example, I have had one TDEV stating that it's 99% used, but when I look in VMware it's only 80%.
Would I benefit from running a Start Allocate/Free/Reclaim on these devices? - I'm just not sure which option to use here: - Reclaim volumes?
Also, with all the changes that happen with VMware, migrations and deletions I seem to recall an unmap command in vmktools for esxi. My colleague had to do it with our XtremIO array, so I am wondering if it's the same situation as with the VMAX.
Thanks!
KW160
121 Posts
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January 21st, 2017 10:00
VMware Unmap is still the right way to go on this. The array-side reclaim will only detect blocks of zeros. It is likely that on disk these are non-zero blocks since they have been written to in the past by this host. Only VMware will be able to tell the array which tracks can be discarded.
CRodolfo
4 Posts
1
January 24th, 2017 13:00
Thank you. Yes, I started to do the reclaim from the VMware side and it works like a charm! It was never done before so I was able to reclaim 11TB and not even half way through all the datastores.