I recently installed rsnapshot and trying to get it to do incremental backups. Now, I run first "rsnapshot alpha" and it creates alpha.0. Folder is 8GB

Then I add a 1 GB video file to the source folder. I would expect the next backup to only be 1GB but ...

after I run "rsnapshot alpha" again via cron job and it renames alpha.0 to alpha.1 - nothing strange here as this is what its meant to do - but the folder is 9GB (8GB original folder plus 1GB video file). That is not what I was expecting as this is going to eat into my storage rapidly.

Isn't the point of using rsnapshot that it allows you to save space by doing incremental backups?

Is this possibly to do with rsync_short_args and rsync_long_args in the rsnapshot.conf file?


1 Answer 1


Backup utilities like rsnapshot, dirvish and MacOS's Time Machine save space by creating hard links in the backup directories between files that haven't changed since the last backup. So recent backup directories appear larger than older ones but recent backups are reusing many of the same files and thus saving space.

  • Ok, that's interesting. So if I understand what you are saying, basically, the first time a backup is created (8GB), all files are copied (8GB). Then I add 1GB to the folder. The second time its launched, only 1GB of files in the folder are actually copied over to alpha.0 while the other 8GB are hard linked to alpha.1. Therefore, if I do a "du -h" on alpha.1, I will get 8GB and if I do "du -h" on alpha.0 I will get 9GB. I confirm that this is actually what happens.
    – MiniTux
    Oct 20, 2018 at 7:39
  • Actually, if that is what happens, then if I remove alpha.0, shouldn't alpha.1 be 1GB? And also, if these folder are actually using up 8GB+9GB=17GB on my drive (thats what "du" tells me), this to me is a false incremental backup systems as my had disk space will run out very quickly. Surely I am missing something here. Otherwise this doesn't make sense as a backup strategy? It would be helpful if someone could shed some light on this.
    – MiniTux
    Oct 20, 2018 at 7:44
  • @MiniTux Do du on both folders in the same command.
    – Kusalananda
    Nov 7, 2018 at 14:52
  • I'm still trying to get around understanding how Rsnapshot actually uses disk space. Tonight I copied a backup folder on my server (a client that does rsnapshot to a server) to an external disk only to find out that the disk ran out of space. I'm going to copy to another post as although its linked to this question its probably slightly off topic.
    – MiniTux
    Jan 6, 2019 at 22:10

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