it would be possible to force it via command line to use the same key for both backup drives, but I did not bother
My apologies for posting to a pretty old thread, and I will start a new one if that is more appropriate, but I was specifically interested in exactly the option mentioned here by
@Dusan - how would I encrypt multiple volumes with the same key?
I understand that it might be difficult to imagine why one would need that. Let's say I have a set of drives in a volume that will be used as primary in my FreeNAS machine. I also have a backup set of drives. I need to protect the drives when at rest with encryption, but I could do without the extra level of passphrase protection. The problem is that the users who will be operating the machine on a daily basis will not have root privileges, and thus would not be able to import, say, the backup volume after the primary has been used or vice versa. (I do that via Web Interface, something that as non-root they would not have access to. And, I imagine, if there were a way to do this via a command line, root privileges would still be required.)
So, I thought, if the two volumes had the same key, which is stored in /data/geli, the users might be able to swap the volumes seamlessly, not having to do anything extra to decrypt them. Is this assumption even correct? Obviously, I cannot test it until I can first create two volumes encrypted with exactly the same key...;) If this assumption is not correct, and even with the two volumes encrypted with the same key the volume swap is non-seamless, could you think of another solution to my dilemma?
Many thanks!