ONTAP Discussions

Windows LUN space reclamation - space-allocation - not freeing blocks

pedro_rocha
361 Views

Hello,

 

Environment is:

Windows Server 2016, ONTAP 9.5, LUN is thin, NTFS formatted, space-allocation WAS NOT enabled

On the host side LUN is 70% occupied, on the storage side, it is 100% full. On Windows, DisableDeleteNotify = 0

 

After reading several KBs, I am still in doubt. Some say you cannot enable space-allocation with the LUN online, some say you need to reboot the server after enabling it, some say you can enable space-allocation and just run a rescan on the host side.

 

Fact is that after enabling it with the LUN online and running a rescan, blocks are still provisioned on the storage side. I tried to create a new file inside the LUN and then delete it (there's a KB stating that this could trigger the UNMAP process).  No luck.

 

Does anyone know the correct procedure?

 

Regards,

Pedro

7 REPLIES 7

Ontapforrum
351 Views

Please check this: (You might be hitting this bug, as you mentioned 9.5)
https://mysupport.netapp.com/site/bugs-online/product/ONTAP/BURT/1227997

 


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


This bug is reported to be introduced in ONTAP 9.5. This bug is resolved in ONTAP 9.5P3+ and 9.6+

Hi, I don't think it is this bug. I forgot to mention we are running 9.5P5 (which has that fixed). 

Ontapforrum
334 Views

Just going by the official NetApp documentation (Not kbs), it does clearly state: You must take the LUN offline to enable space allocation. I think if you just follow the 5 steps in the doc below, it should work.


Enable space allocation for SCSI thinly provisioned LUNs:
https://docs.netapp.com/us-en/ontap/san-admin/enable-space-allocation-scsi-thin-provisioned-luns-task.html

Yes... I saw that and you are probably correct.

 

But than I saw thus: https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Storage_auto-reclamation_does_not_occur

 

"It is recommended to take the LUN offline to enable space allocation but for modern Host OS this is not strictly necessary if a rescan of the SCSI device updates as thin provisioned."

 

We'll try taking the LUN offline...

Ontapforrum
323 Views

Yes, go ahead.


I read that line - Modern OS, it is confusing, and I wonder which OS , further even if the Host is re-sending the scsi_inquiry (as part of the scsi_bus_scan) it is still picking up "old" data from the storage. Therefore,  LUN must be taken offline so that the "SCSI inquiry" data on both nodes in the HA pair is updated.

We have done all... offline/online the LUN, rebooted the server. No changes...

 

I have a opened case, we'll see what support says

Ontapforrum
137 Views

Sure, do let us know how it turns out.

 

In the meantime, could you share screenshot/output of the storage side space consumption and on the NTFS side.

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