If your VMFS5 datastores use the ATS+SCSI locking mechanism, you can change to ATS-only locking.

Typically, VMFS5 datastores that were upgraded from VMFS3 use the ATS+SCSI locking mechanism. If the datastores are deployed on ATS-enabled hardware, they are generally eligible for an upgrade to ATS-only locking. Depending on your vSphere environment, you can use one of the following upgrade modes:

The online upgrade to ATS-only is available for most single-extent VMFS5 datastores. While you perform the online upgrade on one of the hosts, other hosts can continue using the datastore.

The offline upgrade to ATS-only must be used for VMFS5 datastores that span multiple physical extents. Datastores composed of multiple extents are not eligible for the online upgrade. These datastores require that no hosts actively use the datastores at the time of the upgrade request.


You must perform several steps to prepare your environment for an online or offline upgrade to ATS-only locking.


If a VMFS datastore is ATS-only compatible, you can upgrade its locking mechanism from ATS+SCSI to ATS-only.