I am dealing with a virtual machine that is receiving the following entry in the event log:

TIME OF EVENT: 7/30/2011 3:47:05 PM
DESCRIPTION: The device, \Device\Harddisk3\DR3, has a bad block.

Pretty standard fare if this was a physical server, but I need to determine if this is an issue with a .vmdk file have a 'virtual' bad block or if this is occurring because of a physical disk on the SAN.

Is there a way to determine this without taking the VM offline?

  • 4
    What OS? What hypervisor? – KCotreau Jul 31 '11 at 20:29
  • I would think that if there was a disk error you would see it in the log of the physical machine also. On the other hand, I can't imagine how a virtual machine could throw a disk error without the physical disk having an error. – Loren Pechtel Jul 31 '11 at 21:23
  • 1
    Cosmic rays. I'm not really being facetious. It is possible for there to be a corrupted byte in the virtual drive that does not correspond to a real bad block. – Abraxas Jul 31 '11 at 22:00
  • Have you done a chkdsk on the problem partition? – mdpc Mar 8 '15 at 5:49

It's always possible that there is no bad block. I had that happen before. Running chkdsk /b on the drive fixed that problem. But the VM would need to be offline for that.

Testing both the real drive and the virtual one could be done with Windows running using HDTune. Use the full scan and look for the bad block(s). It isn't the best tool in the world, but it has the advantage that it runs in Windows and you can keep your VM running.


One possibility is that OS is not tunned to use Virtual Disk in virtualization. There can appear unusual to real phusical disk timouts. To resolve this you need to finetune OS Disk Timeoute parameter:


  • Select Start > Run.
  • Type regedit.exe, and click OK.
  • In the left-panel hierarchy view, double-click HKEY_LOCAL_MACHINE > System > CurrentControlSet > Services > Disk.
  • Double-click TimeOutValue.
  • Set the value data to 0x3c (hexadecimal) or 60 (decimal) and click OK.
  • Reboot guest OS for the change to take effect.

Instructions taken from here: https://www.vmguru.com/2012/03/set-timeout-on-windows-guest-os-to-avoid-blue-screenserrors/

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