RN104 for mirror and backup

jmazz wrote:

Would the following work ... (1) Setup RN104 using FLEX RAID ... Install 2x 4TB drives in bay 1 and 2 leaving other 2 bays empty. Use RAID 1 on these two drives. (2) In future add 4TB drives to bays 3 and 4 using JOBD (Giving me 3 volumes) (3) Backup volume 1 (from bay 1 and 2) to bay 4. Remove hdd from bay 4 and keep in a safe place offsite as a backup. Replace hhd in drive 4 with a new hdd. Please comment on this procedure and give any warnings of what may go wrong.

For me, it would be best that you backup that data (from volume 1) to an external drive.

jmazz wrote:
If the RN104 fails will I be able to recover data stored on hdds in a new RN104 or similar device?

This is possible as long as the drives are still healthy. However, it would be advisable not to just rely on your current backup using your NAS and to have another backup of your data to another destination for example to an external drive or another NAS.