UnRAID - Backing Up Using Rsync

PRE-REQUISITES
- Rsync plugin
- User Scripts plugin (if you want to schedule the jobs)
- Unassigned Devices plugin

RSYNC TO UNASSIGNED BACKUP DRIVE
I often configure rsync jobs to backup critical data to an unassigned drive outside the array.  My scheduled job looks something like this:

rsync --archive --delete /mnt/user/SourceFolder/ /mnt/disks/TOSHIBA_MD05PBA60_1900876554/DestinationFolder/

RSYNC TO ARRAY BACKUP DRIVE
I read about a very interesting alternative backup approach with UnRAID.  Instead of creating an unassigned drive to use for the backup, you actually add it to your array.  Configure your shares to never use this drive.  The idea here is that the backup drive will be a member of the array, but completely excluded from any and all shares.  Then setup an rsync job like this:

rsync --archive --delete /mnt/user/SourceFolder/ /mnt/disk4/DestinationFolder/

* Where disk4 is your backup disk.

An advantage to this approach is that the backup drive is an array member, so it's protected by parity.  A disadvantage is that the drive is an array member, so it's not as easy to just pull the backup drive out if necessary.  One scenario that comes to mind is if you want to rotate the backup drive with another one (e.g. off-site).  Physically pulling the drive would affect the array and parity would have to be rebuilt.  It would be easier to use an unassigned drive in that scenario.