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Space reclaim and performance
Posted: Wed Oct 22, 2014 1:45 am
by frpaulsen
We have a VMware virtual volume where we do not see that the 3PAR reclaims space. VMware has provisioned 840 GB, but the reserved user size on the 3PAR is 1283 GB (used user size 658). We have several times run the UNMAP command in VMware (5.5), but we do not see any big changes. We have done this with success before. It looks like the AO on the 3PAR puts the unused space on NL disks (currently 687GB). I believe this means that any new data written to the virtual volume will hit the NL disk and give us very bad performance. Is this correct? Does anyone have an idea on how to fix this? We are running 3.1.3 MU1 and P05.
Re: Space reclaim and performance
Posted: Thu Oct 30, 2014 5:02 am
by RitonLaBevue
The right value to look at is "Used User".
For more information about difference between Reserved and Used, have a look to Concept Guide.
Since last 3.1.2 the way reserved space is reclaimed has changed: it takes longer. But that space is still usable by the CPG and so, by the VVs provisioned from this CPG.
Re: Space reclaim and performance
Posted: Mon Nov 03, 2014 3:22 am
by frpaulsen
My problem is related to the growth of the VV and not the data that currently exist on the "Used User". My understanding is that the growth will be written to the reserved user space. The reserved user space is located at the NL disk because it has not been accessed.
I was recommended by HP to upgrade to 3.1.3 because space reclaim should work better which it actually did on several of mine VVs, but not this VV.
Re: Space reclaim and performance
Posted: Mon Nov 03, 2014 5:46 am
by woodunn
RitonLaBevue wrote: Since last 3.1.2 the way reserved space is reclaimed has changed: it takes longer. But that space is still usable by the CPG and so, by the VVs provisioned from this CPG.
Since moving from 3.1.2 to 3.1.3 we have noted the reclaim is actually taking longer. We are waiting on a response from HP