2018-04-13 Backup Format

A discussion on Mastodon about the file formats of backups led me to think it through again:

First things first: I have two sets of hard disks for backups, one for each laptop. We keep one set at the office at all times. We make occasional backups on one set, and take it to the office, and we bring back the other set. This protects us against theft and fire.

I started using Borg Backup last year.

I don’t care about the file format used per se. I still feel that a backup solution should be very robust and that robustness should be more important than deduplication and all that, and that’s why I really liked my old rsync based backup. But setting it all up to have multiple linked snapshots would have been hard, too.

My measure of robustness is perhaps colored by the occurrence of bad sectors in the old days of floppy disks. Thus, a format is robust if I can still read the rest using a tool. That disqualifies compressed data, encrypted data, or anything else that results in a dependency on bytes in the damaged sectors (virtual file systems and the like). Basically, anything but plain text. 🧐

In my situation, I decided I valued encryption more than robustness because I am keeping external disks outside our home. Given that this already results in an opaque byte soup, I decided I might as well use any other format (Borg Backup, whatever). That’s for making backups of my laptops to keep them outside our home.

On the other hand, when making backups of my servers to my laptop, the situation is different: encryption is not essential, and plaintext is robust, and that’s why I use rsync.

Anyway. The most important part is to make backups. Any kind of backup will do. And check whether you know how to recover files from the backup!



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