@Paul wrote in this thread that in DSM you can’t use a standalone HDD in one of the NAS bays for server backup and rotation, i.e. hotswap & exchange two drives, and always have one offsite. The only way is to use USB DAS. This is a bummer, because I wanted to do the same, so the chances of me buying a Synology have dwindled further.
My plan is to use one SATA lane for a hotswap 3.5" HDD, and run nightly backups from the main storage pool (ZFS) to the HDD (simple clone, not incremental). The backup volume itself would be formatted as ext4, so I can also access the data with my Mac. (Paragon’s Linux drivers only support ext4, not btrfs, and I’m not sure if OpenZFS for macOS is a good idea.)
The backup HDD would obviously be a standalone/unassigned drive.
Since TrueNAS Scale and unRAID are imho not a proprietary walled garden like Synology’s DSM, at least not as much, my question is: is this possible on TrueNAS Scale and unRAID? Or are there restrictions similar to DSM?
(I faintly remember reading somewhere that, for example, it isn’t possible to format an unassigned drive with ext4 in TrueNAS. Correct?)