topic Re: Space Reclamation not working in ONTAP Hardware

Space Reclamation not working

OmotayoZadok — Wed, 04 Jun 2025 10:13:43 GMT

Hi,

I have a thinly provisioned LUN from my FAS2552 to a Windows Server 2019, with hyper-V role installed.

On the server, it shows that the free space is 246GB. However on the storage, we have about 178GB left.

I have run the commands on the Storage SSH to fix this. (I disabled and enabled the space-allocation feature)

ONTAP version is 9.5P17.

Please help me with suggestions to fix this anomaly.

Re: Space Reclamation not working

pedro_rocha — Thu, 16 Sep 2021 17:38:21 GMT

Hi,

Did you check this KB?

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/ONTAP_and_Windows_SCSI_unmap_and_space_reclamation

It does not list 2019, but I guess is just out dated.

Also, when setting space-allocation, are you putting the LUN offline and re-discovering it?

Re: Space Reclamation not working

jaikumar — Thu, 16 Sep 2021 19:21:49 GMT

To confirm if after enabling space allocation , you can check if the counters related to space reclamation operations at the hosts incremented in the target

unmap_reqs

These counters are in the lun object

e.g statistics show -object lun -instance <lun path> -raw -counter *unmap*

(space reclamation sends scsi unmap commands to the target and scsi unmap requests is expected to increment the above counter)

Re: Space Reclamation not working

OmotayoZadok — Fri, 17 Sep 2021 10:01:44 GMT

Yes. I set the LUN to be offline before running the command