Unmounting and detaching VMFS volumes

Unmounting a datastore is done when you intend to preserve the data on a VMFS volume, but still remove access to the volume. Detaching is performed on a LUN device and it is done to make sure that the access to the LUN is gracefully removed. It is recommended you unmount a VMFS datastore and detach its corresponding LUN device, before the LUN backing it is unpresented from an ESXi host.

Getting ready

Make a note of the NAA ID of the LUN corresponding to the VMFS volume. This can be done by selecting the datastore and navigating to Configure | Device Backing:

Alternatively, you can issue the command esxcli storage vmfs extent list:

It is advised that you take care of the following before you proceed with the unmount operation:

• All the VMs should be migrated off to a different datastore
• The datastore should be removed from a datastore cluster
• The datastore should remain unmanaged by Storage DRS (SDRS)
• Storage I/O Control (SIOC) should be disabled for the datastore...