I noticed that compression keeps coming up as a topic for restic. As far as I understand, fd0 confirmed in 2019 that restic will support compression at some point but, for now, it’s still on the to do list.
So, if compression is not available, then how come that the KVM qcow2 file I backed up with an original size of 70G only takes up some 20G in the repository? I mean, I understand that I allocated a lot more space to the VM than it currently takes up and that for the largest part, the file consists of zeroes. Still, without compression, how is restic able to reduce the snapshot size?