Snapback2 does backup of systems via ssh and rsync. It creates rolling "snapshots" based on hourly, daily, weekly, and monthly rotations.
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You might think this would take up lots of space. However, snapback2 hard-links the files to create the images. If the file doesn't change, only a link is necessary, taking very little space. It is possible to create a complete yearly backup in just over 2x the actual storage space consumed by the image.