Restic upgrade on Debian Buster
A while ago I switched backups from "Duplicity" to "Restic". About time: I was using Duplicity for many years (I think I started using it around 2010, long before "Restic" became available) and it served me well. But recently I ran into more and more issues, especially with archives getting larger and larger. There is an 11 years old open bug in the Duplicity bugtracker, which describes a showstopper for backing up larger archives. And it doesn't look like this will be solved anytime soon. Therefore it was time for something new.
Since I'm rolling out my backups with Ansible, it was relatively easy to create a set of scripts for Restic which use almost the same infrastructure as the old Duplicity backups. That works as expected on all our laptops. But the Raspberry Pi, which does the fileserver backups, seem to had a problem. Backups took way longer than before, jumped from 30-60 minutes (depending on the amount of changes) to constantly around 10 hours.
After some investigation (means: --verbose --verbose --verbose debugging), it turns out that Restic identifies most of the files as new, even though they did not change at all. Some background information: the Raspberry mounts the QNAP fileserver using the SMB3 protocol. The "mount -t cifs" uses the "serverino" option, but apparently that is not enough to provide a stable inode number. And if the inode for a file changes, Restic assumes it is a new file.
On the bright side, because the content of the files do not change, the deduplication still works, and no additional content is added to the backup. The size of the backup does not increase. Still, Restic fetches all the data from the server, and that takes a long time.
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