Note: Please be advised that changing the Disk ID of a volume hosting the OS is not recommended as it will cause the machine not to boot. 

In some cases if a VM has the same Disk ID as the host, Microsoft VSS will fail and thus backups will not be successful. In such cases you will need to change the Disk ID as below.

To view the Disk ID:

1. Open Command prompt
2. Enter the command  DISKPART and hit enter
3. Enter the command LIST DISK  and hit enter to list all available disks
4. Enter  SELECT DISK X (Substitute  "X" for the number of the disk you wish to select) and hit enter
5. Enter  UNIQUEID DISK  and hit enter
6. A four byte disk ID will be returned, for example: "e9eb3aa5"

To change the Disk ID:

1. Open Command prompt 
2. Enter the command  DISKPART and hit enter
3. Enter the command  LIST DISK  and hit enter to list all available disks
4. Enter  SELECT DISK X (Substitute  "X" for the number of the disk you wish to select)
5. Enter UNIQUEID DISK ID=a4e19dc0 and hit enter
6. This will change the Disk ID to "a4e19dc0"
7. Enter  UNIQUEID DISK  and hit enter to view the new Disk ID