ONTAP Discussions

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

pedro_rocha
2,030 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
2,020 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+

pedro_rocha
2,012 Views

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

Ontapforrum
2,003 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

pedro_rocha
2,001 Views

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
1,992 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.

pedro_rocha
1,820 Views

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
1,806 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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