Restic (backup) deleting old backups is extremely slow

Sunday, March 18th, 2018

Here’s a very quick note:

I’ve been using the Restic backup tool with the SFTP backend for a while now, and so far it was great. Until I tried to prune some old backups. It takes two hours to prune 1 GiB of data from a 15 GiB backup. During that time, you cannot create new backups. It also consumes a huge amount of bandwidth when deleting old backups. I strongly suspect it downloads each blob from the remote storage backend, repacks it and then writes it back.

I’ve seen people on the internet with a few hundred GiB worth of backups having to wait 7 days to delete their old backups. Since the repo is locked during that time, you cannot create new backups.

This makes Restic completely unusable as far as I’m concerned. Which is a shame, because other than that, it’s an incredible tool.