[alphapapa]

A couple of years ago I went to use GPG for the first time in a long time. My private key didn't work. I looked at the file, and its size was 0 bytes. Cosmic ray? GPG crash? System crash while the file was being written? How it got truncated, I'll never know.

No problem, I'll just restore from backup. I have CrashPlan online backups, and local backups with Obnam, so I'll just recover it from one of them.

Every snapshot in CrashPlan and Obnam had the truncated file, going all the way back to the first snapshots. I thought I had lost my GPG key forever.

Then I remembered that I had some old CD-R/RW backups from years ago. I started going through them. Some of the discs were unreadable. Finally I found one that was readable and had the untruncated private key file.

Lesson learned: always keep your old backups. You never know which files on your system have suffered from bitrot or accidental truncation or accidental deletion--until you try to access them. It's very likely that some of them will have been destroyed more than 30 days ago.

Now keeping old backups doesn't mean keeping every snapshot, ever. CrashPlan takes 15-minute snapshots by default, so obviously I don't need every one of those going back years. But I definitely want to keep at least one snapshot for every year I've used the system, at least one for each of the last 12 months, etc.