Does NVMe support WEAR(Write Exclusive All Registrants) capability for clustered VMDK

Applies to

Answer

• No, WEAR is not supported by NVMe for clustered VMDK.
• It is still in the planning stages.
• However, this is supported for FC and ISCSI.
• It is seen clustered VMDK supported option is set to No for NVMe & Yes for FC.

• Similarly from ESXi CLI below is seen for NVMe and FC respectively.

vsish -e get /storage/scsifw/devices/uuid.bb9xcxcxcxcxcxcxcxcxcxa38/info
is WEAR reservation supported?:0

vsish -e get /storage/scsifw/devices/naa.600xcxcxcxcxcxcxcxcxcx496f/info
is WEAR reservation supported?:1

Additional Information

• Clustered VMDK - VMware introduced this feature in vSphere 7. It is an attribute of a VMFS6 datastore which can be enabled on a new datastore.
• When a VMFS has clustered VMDK enabled (BTW vVols datastores don’t have this feature), it means a vmdk can be shared with multiple VMs.
• SCSI3-PR is used for I/O fencing, which basically means it controls the access of multiple nodes to the same device.
• SCSI3-PR has a number of different types including WEAR:
  • Write Exclusive (WE)
  • Exclusive Access (EA)
  • Write Exclusive Registrants Only (WERO)
  • Exclusive Access Registrants Only (EARO)
  • Write Exclusive All Registrants (WEAR)
  • Exclusive Access All Registrants (EAAR)
• What are SCSI Reservations and SCSI Persistent Reservations?