Hey everyone, [NOBAK] should work for all types of backup: Rolling Snaphost, Disaster Recovery, Continuous Replication, Full Backup and Delta Backup.
Unfortunately, due to the way the snapshot process is implemented in XCP-ng, ignored VDIs will still be snapshotted before being deleted, which takes time and space unnecessarily, but we have discussed with the XCP-ng team and they are working on improving this 🙂
In the meantime, XO tries to work around this by temporary detaching these VDIs from the VM during the snapshot, but this only work when the VM is halted (see offline backup in the advanced settings of a backup job).