reclaim storage from VMFS volume

RANJBASSI — Wed, 04 Jun 2025 23:47:21 GMT

Hi All

Hoping someone can help me on the NetApp forums as I have been going around in circles on this one, both with NetApp and VMware.

We have a NetApp FAS8020 array where we present Fibre channel LUNS to ESX. All are flexvolumes which are thin provisioned and the LUNs are also thin provisioned. Fractional reserve is NOT set. I am looking to reclaim space from our volumes to increase our aggregrate free space ready for a migration project which will require some significant space.

For the NetApp suite we have the option to reclaim space using the NetApp Virtual Storage Console (VSC) vcentre plugin however this is only supported on NFS volumes.

Is there any other way to reclaim space on Fibre based LUNs using VMFS?

I have tried the ESXi CLI tool vmfkstools -y command however whilst this runs, it doesn't ever reclaim the space and there is a KB article for this issue http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=2048466

however all of our volumes are VMFS-5 and have a GPT partition table and all have been provisionned using the Vcenter provisioning new storage wizards.

We are using ESXi 5.0.0 U3 both Hypervisor and vCentre level. our NetApp is running Data ONTAP 8.2.1 7-mode.

There is a NetApp KB which discusses which what VAAI operations are supported and our evnironment seems to be ok for being able to reclaim space

https://kb.netapp.com/support/index?page=content&id=3013572

Does anyone know if these issues are resolved in vSphere 6 as we are looking to upgrade to that, I am thinking maybe doing the ESX upgrades first. My plan was though to upgrade to the 8.2.3 of DataONTAP first ideally.

Many thanks

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reclaim storage from VMFS volume