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.
  • Verify that the guest operating system of the virtual machine supports a watchdog timer:
    • Windows Server 2003 supports a Watchdog Resource Table (WDRT) and Windows Server 2008 and later supports a Watchdog Action Table (WDAT). The guest operating system does not require additional configurations.
    • The Linux distributions, such as Ubuntu 18.04 and Red Hat Enterprise Linux 7.6 based on 4.9 or later kernel, support 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.