Backups with restic, finally
After the ZFS migration I had nice local snapshots, but snapshots on the same disks are not a backup. If the machine dies, catches fire or gets knocked over by a cat, the snapshots go with it. I had been putting off a proper backup setup for far too long.
I tried a few tools and ended up with restic. It is a single binary, the repository format is well documented, encryption is on by default and deduplication works well for my mix of photos and small text files. The first full backup of roughly 1.2 TB took a night and most of the next morning.
There are two repositories. One is on an external USB drive that is plugged in on Sundays. The other lives on a small machine at a relative's house and is updated nightly over SSH. A systemd timer runs the backup, then a forget and prune with a retention of 7 daily, 5 weekly and 12 monthly snapshots.
The part I am most pleased with is the restore test. Once a month a script picks a few random files, restores them to a temporary directory and compares checksums with the originals. If anything differs, I get an email. So far it has only failed once, and that was a typo in the script.