I have a Linux install with two user accounts which I want to back up, either to a single repository or separate ones. What’s the best way to pull this off? I was thinking of multiple ways:
Install and run it as root, so it should be able to access both users? Are there security repercussions?
Having two Backrest installs, how to do it without them overlapping?
Giving the systemd service access to both /home folders somehow?
Creating a shared user group which both users belong into, and assigning both /home folders to the group. New files would still have the wrong ownership though and it seems troublesome to maintain.
There is probably not one correct answer to your question and there are a few points missing in your description like whether the two users trust each other and what risks you want your backup to mitigate.
Take a look at the 3-2-1 backup rule. If your users trust each other and have a lot of overlapping data, using a single repo might save you space with restic’s deduplication functionality. On the other hand you will want to have backups in a separate location. Also you’ll want to test restores from time to time to be sure they work. After all, you do the backups so you can be sure the restore works if you really need it.