[rdiff-backup-users] incremental or differential backup

[Michael Biebl]

Hi,

I'm new to this list, so if this question has already been answered
please bare with me and point me to the relevant discussion.

I was wondering, if rdiff-backup stores the snapshots differentially
or incrementally

Say, I create a snapshot every day.
If I want to restore a file from 15 days ago, do I need all 15
snapshots to restore the state (incremental) or only the current
up-to-date state + 1 rdiff (differential)?

If rdiff-backup only allows incremental backups, I see the following problems:
1.) If a file changes a little every day (big mysql db), then
restoring the file (from say 100 days ago) will probably take a lot of
processing time, space and memory.
2.) If one of the rdiffs goes corrupt (e.g. via a bad sector), all my
older backups are broken.
3.) I can't throw away rdiffs, say I want to create daily snapshots,
keep 30 of them, then keep monthly snapshots, and so on (basically
what tools like rsnaphost provide).

I couldn't find any obvious answer in the documentation, so I'd be
very thankful if you could help me with this questions.

Cheers,
Michael

-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?