ESXi 5.1 SCSI UNMAP working yet?

[russ79]

I keep reading that its working for VMware View... which we dont use... is there any info on if SCSI UNMAP is supported for regular VMs? How to enable / test it? I've done the vmkfstools -y <% of lun> command as a test in 5.0... i was hoping for a better solution or fix in 5.1

[peetz]

My understanding is that ESXi 5.1 does NOT yet use the SCSI UNMAP command automatically and pro-actively, but only on demand.

E.g. when you wipe and then shrink a Space Efficient (SE) Sparse Disk. This is a new virtual disk type that was introduced with ESXi 5.1 and allows for virtual SCSI UNMAP commands from the guest OS to the VMKernel layer and physical SCSI UNMAP commands from the VMKernel layer to the Storage array. For details see the What’s New in VMware vSphere 5.1–Storage white paper.

- Andreas

[russ79]

thats disappointing.... i still don't quite grasp how the vmkfstools -y command works... do you know of any useful documentation on it? I tried it on one LUN and never did anything more with it... can it be disabled again? I feel like there isnt a whole lot of info on this thing... 

[mcowger]

vmkfstools creates file that is X% of the free space on the disk, and then deletes it, sending relevant UNMAP commands along the way.

It works fine, as long as your array supports it.  If your array doesn't support UNMAP, then it will do nothing

[gman18480]

I got a tool I made for this exact purpose. It utilizes vmkfstools -y . Check it out here DaWolf VCP: SCSI Unmap Tool for ESXi5.0 / ESXi5.1