Hello! I just set up timeshift on my EndeavourOS pc, but this time I chose BTRFS instead of rsync. I currently decided to store the snapshot on the same hard drive of my installation because, well, it’s my only one. during the setup, it only asked me if I wanted to include the @home or not. using rsync, instead, it asked for a bunch of locations, and I could choose to include only dotfile, everything, nothing,… is this normal?
also, the snapshot took like… 1 second? with rsync it may take up to 5 minutes… is this normal? or am I backupping fried air?

  • tubbadu@lemmy.kde.socialOP
    2·
    1 year ago

    so it is a completely different process than with rsync… I always thought of the two ways are pretty similar

    • tychosmoose@lemm.ee
      2·
      1 year ago

      Copy on write is the difference. As I understand it, a btrfs snapshot takes no space when it’s created (beyond the file system record). The filesystem is always writing changes to file chunks as a new copy of the chunk, which is then recorded as a replacement of the old chunk (which is still present on-disk). So a snapshot tracks all of these later changes, and the file system keeps the old file chunks preserved as long as you keep the snapshot. That’s why you can mount a btrfs snapshot. It just shows you the volume through the lens of all of these saved changes.

      When you delete a snapshot you are then marking these preserved chunks as free space. So that is also quick.