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I have a very strange situation. I have a Windows 2012 R2 VM with mounted thin provisioned LUNs located on a NetApp FAS2552 filer (running cDOT 9.4P2), and the server is not sending SCSI UNMAP commands when files are deleted from the LUNs.

Things I have tried:

  • C:\Windows\system32>fsutil behavior query disabledeletenotify (returns 0)
  • Restarted the client OS
  • dismounted and remounted the LUN

I have verified that there are no UNMAP commands being received by the toaster by doing a statistics run on the LUN while deleting files, and looking at the counters as suggested here: https://kb.netapp.com/app/answers/answer_view/a_id/1002617/~/faq---windows-scsi-unmap-

I opened a case with NetApp, and they are claiming that, because the host is not sending unmap commands, it is an issue that I need to take up with Microsoft.

So I came here first... anyone have any idea how to figure out why this host is not sending unmap commands when files are deleted?

Glenn Sullivan
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  • For the article you linked, it seems that different Microsoft DSM version required different `disabledeletenotify` setting (ie: 1 vs 0). Have you tried flipping it? – shodanshok Sep 19 '19 at 19:19
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    Check that Windows actually recognizes the disk as thin provisioned, e.g. with `Get-Disk -Number # | select -Property ProvisioningType`. If it doesn't say `Thin` then you need to have a much longer chat with the NetApp admins, or NetApp themselves. – Michael Hampton Sep 20 '19 at 00:33

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