When you create a VMFS5 datastore on a device that supports atomic test and set (ATS) locking, the datastore is set to use the ATS-only locking mechanism. In certain circumstances, you might need to downgrade the ATS-only locking to ATS+SCSI.

You might need to switch to the ATS+SCSI locking mechanism when, for example, your storage device is downgraded or firmware updates fail and the device no longer supports ATS.

The downgrade process is similar to the ATS-only upgrade. As with the upgrade, depending on your storage configuration, you can perform the downgrade in online or offline mode.


  1. Change the locking mechanism to ATS+SCSI by running the following command:

    esxcli storage vmfs lockmode set -s|--scsi -l|--volume-label= VMFS label -u|--volume-uuid= VMFS UUID.

  2. For an online mode, close the datastore on all hosts that have access to the datastore, so that the hosts can recognise the change.