When you create a VMFS5 datastore on a device that supports atomic test and set (ATS) locking, the datastore is set to the ATS-only mode. In certain circumstances, you might need to turn off the ATS mode setting.

Turn off the ATS setting when, for example, your storage device is downgraded or firmware updates fail and the device no longer supports hardware acceleration. The option that you use to turn off the ATS setting is available only through the ESXi Shell. For more information, see the Getting Started with vSphere Command-Line Interfaces.


  • To turn off the ATS setting, run the following command:
    vmkfstools --configATSOnly 0 device

    The device parameter is the path to the head extent device on which VMFS5 was deployed. Use the following format:

    Note: It is sufficient to run this command on one of the ESXi hosts sharing the VMFS5 datastore. Other hosts automatically recognize the change.