Is a bad block on a virtual machine a virtual or physical issue?

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
EVENT LOG: System
EVENT SOURCE: disk
EVENT ID: 7
SEVERITY: Error
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?

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.