Snapshots explanation

A snapshot represents the state in which the source directory was, at a certain point in time. For each new snapshot only new and changed files are added; files that remain identical between the snapshots are created as hard links. This way backups remain slim even if there are plenty of snapshots.

Example:

If you have this snapshot config in config.yaml for a backup:

...
rsync_src: sample/src/dir
rsync_dest: sample/dest/dir
...
snapshots:
  hourly: 6     # Keeps a snapshot each hour for the last 6 hours 
  daily: 7      # Keeps a snapshot each day for the last 7 days.
  weekly: 4     # etc..
  monthly: 6
  yearly: 3
...

the resulting backup directory structure for sample/src/dir will look like this (after some years):

Each snapshot directory contains the state of the backup source from a certain point in time.