All, does anybody have experience using the space reclamation commands in vSphere 5.1 for thin-provision array volumes (i.e. all-flash arrays)?
Here's the EMC documentation on it:
Reclaim command
# cd /vmfs/volumes/volume_name
# vmkfstools -y percentage_of_deleted_blocks_to_reclaim
My question has to do with the percentage you give the command and the potential issues that could happen if the command is not correct.
In order to perform the free-block reclamation, ESXi creates a temporary file that is sized based on the percentage you list in the command. You've gotta be careful when doing this as you could potentially fill up a production datastore and freeze the VMs on it.
Please tell me if my thinking is correct on this example.
I have a 2TB VMware Datastore and it shows 93% full (7% free) on the array side (vCenter shows more like 15% free space).
I would want to run the command with a very small percentage so as not to risk filling up the datastore during the reclaim operation. If I choose to reclaim 2%, the correct command would be:
# vmkfstools -y 2
Is this command format correct? I would fill up the datastore up to 95% temporarily while the reclamation operation is running, right? Then the 40GB (2% of 2TB) temporary file would be deleted and I would gain back an additional 40GB on my 2TB datastore, dropping the used percentage to 91% used instead of 93% used, correct? I would just keep repeating the command until I have enough free space to use a higher, more comfortable % in my command and/or until I can no longer reclaim any free blocks.
Does this sound good? EMC was surprisingly reluctant to help me with this and actually sent me to VMware support. I have not opened a ticket with VMware yet - was hoping someone here has a lot of experience running this command on a thin-provisioned all-flash array.