PROBLEM

When using multiple drive swapping (rotation) as your Offsite copy Location, VM Backup is backing up to the wrong Drive.

CAUSE

VM Backup identifies disks by their Volume ID, if the volume ID of multiple drives is identical, then our software will not distinguish between the two.

SOLUTION

Check that the Volume ID of the disks are not the same.

To view the Volume Serial Number (also called the Volume ID), use the "dir" command from any command prompt as below:

If the Volume ID of the drives is identical, you will need to change it manually. 

To change the Volume ID download the "VolumeID" utility from Microsoft here: http://technet.microsoft.com/en-us/sysinternals/bb897436

From command prompt use the following syntax:

volumeid x: xxxx-xxxx

Where "xxx-xxx" is the new Volume ID you wish to change to. This can be any string of 8 alphanumeric characters, just ensure that each drive has a unique Volume ID. See example below:

Once done, disconnect and reconnect the drive for the change to take effect, if this does not work then reboot the machine.