NetApp cDOT and ESXi SCSI UNMAP support22 Jun 2015
I have recently noticed that LUNs created on NetApp cDOT storage systems by default don’t support space reclamation (aka SCSI UNMAP) which is a part of the vSphere VAAI Thin Provisioning primitive:
~ # esxcli storage core device vaai status get naa.600a0980424733322f5d444f76513730 VAAI Plugin Name: VMW_VAAIP_NETAPP ATS Status: supported Clone Status: supported Zero Status: supported Delete Status: unsupported
and when you try to reclaim space, you are greeted with the following message:
~ # esxcli storage vmfs unmap -l cdot_01 Devices backing volume 549a787c-f5a4021c-e59d-68b599cbd47c do not support UNMAP
Based on a short review of a few systems, this seems to be the case only for the cDOT platform (tested on Ontap 8.2 and 8.3), while LUNs created on 7-mode systems show
Delete Status: supported.
Explanation for this behavior can be found in the NetApp cDOT official documentation, namely the SAN Administration Guide. The document states that in order for space reclamation to be supported on a LUN:
- LUN needs to be thinly provisioned on the storage system
space-allocationoption needs to be enabled on the LUN
Information on how to enable
space-allocation on a LUN is available in the same guide:
lun modify -vserver <vs> -volume <vol> -lun <lun> -space-allocation enabled
What’s a bugger is that the LUN needs to be offline in order to run this command, so best thing to do would be to enable this prior to presenting the LUN to the hosts.
One more thing to have in mind is that the VMware Compatibility Guide explicitly states that “VAAI Thin Provisioning Space Reclamation is not supported” for ESXi >= 5.5, and Data Ontap < 8.3 (both clustered and 7-mode). So, even if your NetApp LUNs are configured properly for space reclamation, be sure that you are running a supported configuration before initiating a SCSI UNMAP operation from an ESXi host.Share on Linkedin | Twitter