I’m using a very similar setup to you but I mirror from my NAS to my ROCK using rsync. I also back up my music library using CloudSync. (Just as an aside, CloudSync on BackBlaze supports versioning and retention of previous versions. This nullifies the concerns about rendering the backup “useless” with accidental deletion or corruption).
The trickiest part was figuring out how to get rsync working. I shared the steps here a while ago:
- In File Services, Enable rsync
- In File Station, Map a remote folder to your ROCK’s InternalStorage folder
- In Task Scheduler, create a task that runs the following command (you may need to adjust paths/host names):
rsync -av --delete --exclude ‘@eaDir’ /volume1/Library/ /volume1/ROCK/Library
In your situation, you would just have to swap the source and destination folders if you want the ROCK to be the source and the NAS to be the backup.