We have a HUS110 with tiering enabled (2 tiers).
We have volumes assigned to VMware (5.5 U2), all volumes are 5TB and all our VMDKs are thin provisioned via VMware.
I'm confused at how "Total Reclaimable" is calculated under DP Optimisation.
For example, I have a 5TB LUN formatted as VMFS and on that VMFS I create a single thin 2TB VMDK.
After some time, when I look the volumes under DP Optimisation that volume will show approx 2.1TB used with 300GB reclaimable - how can the usage on the volume exceed the maximum size of the VMDK when the VMDK is the only thing on it?
Similarly I have volumes where VMware shows there is 900GB in use but under DP Optimisation I see 1.3TB used with 400GB reclaimable - we definitely haven't created or deleted 400GB worth of VM's.
I suspect I'm missing something fundamental but I've read the HUS guide and just don't see it so before I open an SR...
Thanks,
I fought this battle a few months ago.
when a page is moved to a different tier the page the "from" page is not released but remains assigned to the lun. Yep, that is right. thus the "assigned" capacity of the luns grows and grows and grows.
There is a process to reclaim this space but by default it doesn't work well. a lun must have a reclaimable space of 500GB before the reclaim process is run for that lun.
go into the dp optimization and turn on Auto DP optimization for each lun with a trigger size of 10GB. A process runs at midnight and any luns meeting this reclaimable space requirements will have their space reclaimed.
you will still see the space grow during the day.
you can also slow down the page migration rate but that has the side effect of not moving pages as quickly.
BTW, none of this is adequately documented.