Symptoms

You set up a backup plan of Windows machine(s) with Policy Rules: [Disk 0] in Items for backup.

Backup fails with errors similar to:

Cannot resolve inclusion rule '[Disk 0]'.

Disk 0 has not been found while processing the 'Disk by number' template

Cause

Current product design. Acronis Agent starts disk enumeration from 1, not from 0 as Windows Disk Management. 

If Acronis Agent is installed on the machine, you can verify the disk number used by Acronis Agent: choose Directly in Items for back up:

The image below shows the disk layout of the same machine in Disk Management:

Solution

Specify [Disk 1] in policy rules to back up the first disk on the machine. This corresponds to Disk 0 in Windows.

Alternatively, use the rule [BOOT+SYSTEM] to select the system and boot volumes. This combination is the minimal set of data that ensures recovery of the operating system from the backup.