To prevent the virtual machine from a guest operating system failure for an extended period of time, you can add a VWDT device to the virtual machine.


  • Power off the virtual machine.
  • Verify that the virtual machine hardware is of version 17 or later.
  • Verify that the guest operating system of the virtual machine supports a watchdog timer:
    Note: The guest operating system may require you to explicitly enable the watchdog services. Failure to do so might cause the watchdog timer to power off or restart the virtual machine.
    • The VWDT device implements the Watchdog Resource Table (WDRT) and Watchdog Action Table (WDAT) specifications. Windows Server 2003 supports devices compatible with WDRT and Windows Server 2008 and later supports devices compatible with WDAT.
    • The Linux distributions based on 4.9 or later kernel, such as Ubuntu 18.04 and Red Hat Enterprise Linux 7.6, support devices compatible with WDAT if the wdat_wdt.ko driver is available.
    • The watchdog timer is not supported for other guest operating systems, such as FreeBSD and Mac OS X.
  • Required privileges:
    • Virtual Machine.Configuration.Add or remove device
    • Virtual machine.Configuration.Modify device settings


  1. Right-click a virtual machine from the vSphere inventory and select Edit Settings.
  2. On the Virtual Hardware tab, click Add New Device and select Watchdog Timer from the drop-down menu.
    The New Watchdog timer device appears in the Virtual Hardware devices list.
  3. To start the virtual watchdog timer with the BIOS or EFI firmware, select Start with BIOS/EFI boot.
    The virtual watchdog timer starts before the guest operating system boots.

    If the guest operating system takes too long to boot or it does not support the VWDT device, a warning message appears, and the VWDT device might constantly restart the virtual machine.

  4. Click OK.


You can view the status of the VWDT device in the VM Hardware panel on the Summary tab.