Backup Errors

[Cyberfarer]

Greetings, I recently created a new backup. When the backup executed, there was a directory that the backup user could not access resulting in an error as follows:

Command failed: rsync: opendir "/volume1/MIRA/ZZ - MDrive Archive/HR" failed: Permission denied (13)

This resulted in the loss of the Daily backup. The files are in .sync but no Daily.0 is created. Is this expected behaviour? It is not unusual to encounter errors backing up Windows volumes as users will leave files open. I have found that because of such cases I have gaps in my backups.

Is there a way to add fault tolerance? I don't think a backup should "fail" because a file or files could not be included in the backed up for whatever reason.

Thank you.
Sean.