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ONTAP Hardware

Space Reclamation not working




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.



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)




Did you check this KB?


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?





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

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