How to reclaim storage on HP 3Par systems.

3Par does not seem to be that effective at reclaiming space and requires some manual tasks to free up space, due to the detection method which is “Zero detect” or “UNMAP”.

To Release space on VMware

On VMware ESX, if you copy or data migrate 1TB of data from one Datastore to another Datastore: HP 3Par does not see the move and now sees 1TB+1TB of data, since the old data locations are not zeroed out or that VMware does not give instructions to 3Par about the released storage – this feature is also called UNMAP.

This seems to be due to the fact that VMware no longer has the UNMAP feature enabled which reclaims space after data has been deleted or moved


So VMware knows the data has moved and shows correctly in Vsphere console – But since the old data blocs are not reclaimed/zeroed out HP cannot see it and release the space.

Recommendations is to run UNMAP manually by the following command on a datastore trough Putty SSH on a ESX 5.5 host

”Esxcli storage vmfs unmap –l DATASTORENAME”

It will have a small performance impact when run.

ESX less than 5.5 have to use the “vmkfstools –y 80” command on a datastore to create a balloon file with empty data taking up 80% of the free space in this example.

To release space on Windows Servers

When files are deleted in Windows 2003 and 2008, they are not zeroed out which 3Par can detect and release.

UNMAP is supported from Windows Server 2012 + R2 – so this should help 3Par release storage.

Windows Server 2003/2008  server requires Sdelete.exe tool to Zero out data.

Example to Zero out unused disk space on volume Z: “Sdelete.exe –Z J:\ “

Requires volumes to have letters, and from Sdelete version 1.6 you have to use the Z switch (previous –c option)

After data have been zeroed out, it will take some time for 3Par to release the space. HP tells me that the 3Par system will not prioritize this task under heavy load and that there are no way of activate this task manually or see the status of it. Nothing left then to wait and see, HP told me that I should look again after a weekend to see if the data have been released.

The virtual volumes also needs to have “Zero Detect” enabled.


So this is the theory, but I do still struggle with the 3Par to release the space.

In this example, HP 3Par detects that the volume is only 50% filled – but 3Par holds 5.5TB in custod


HP 3PAR Thin Technologies Whitepaper

A easy to understand blog about thin provisioning including Video demonstration


I have used all these commands without issues, but do it at your own risk.