Enabling Space Reclamation

[Tril0byte17]

Hello

I've now completed my update to 12.0 and I'm looking at enabling space reclamation. I cant see any reasion why not or any issues but just wanted to see if anyone has had issues doing this?

Thanks

Adam

[oikjn]

no issues, but it was a bit tricky to actually get it to function and I was upset at first before I figured it out.

First you have to enable it on the SAN, but after that, you have to rescan the drives on the host OSes so that it picks up the  new feature capability list for the LUN.  I think there is a non-disruptive way to do this, but I ended up disconnecting the LUN from the computers (all windows servers), deleting the hidden disks from device manager and then reconnecting the LUNs and then I got the drives to shrink.  When I just did a rescan and that didn't get it to function.

[GlenRB]

I believe if you do a disk defragmentation on the Windows servers - 2012 or newer, this will trigger the space reclamation also.  That is if the Windows server is directly attached to the LUN (ISCSI initiator).  If the Windows server is a virtual machine using a VMDK in VMware, then you have to rely on VMWare to send the commands for space reclamation to the SAN using vmkfstools.

http://vmfocus.com/2015/02/26/how-to-hp-storevirtual-lefthand-os-12-0-with-t10-unmap/

[oikjn]

it isn't just the command for space reclaimation, the disk needs to be marked with the FEATURE of space reclaimation and if that feature isn't enabled, then windows won't send the command.  I believe it is supposed to get added if you do a rescan in partition manager, but I don't think I could get it to work and ended up just unmounting the disks, deleting them from the "removed" items in computer manager and then re-connecting them and I got it working again.

Just bringing this up in case someone tries and can't get it to work and can't figure out how/why.   A new disk created after the space reclaimation function is enabled will automatically have that feature capability included, but a disk added to a server PRIOR to that feature being enabled will NOT have that feature included without additional user intervention.