Re: [Duplicity-talk] Sliding window backup strategy?

[Serge Wroclawski]

> Thank you, that is excellent advice! I was aware of Amanda, but had
> missed this in their docs. Or even forgotten. I've been using Amanda in
> the 90s. Doh. So that's where the idea came from! ;-) Those who forget
> the past ...
> 
> Do you think something likethis would be worthwhile to add to duplicity?
> I like it's simplicity and client-centric / dump-repository approach,
> and of course the encryption etc, which I think would be quite hard to
> add to amanda.

Honestly, I'm not sure I entirely see the point when doing disk to disk backups.

What does a full backup buy you other than needing less files for a restore, 
and why is that important?

When you remove archives older than a certain date, it reconsiles the data so 
you have a full copy of the backup, and full 
backups /are/ expensive, so why perform them if you don't have to?

If you're really concerned about the issue of number of files used in the 
restore, maybe a better feature to focus on might be 
a way to consolodate the backups without removing old achives, but I'm guessing 
the reason that no one has down that as an 
explicit command is that there isn't much demand for it.

> Basically, it boils down to marking n% of the files dirty regardless of
> whether they have changed or not - how hard can that be?

But why transfer them if they haven't changed? You are just adding overhead to 
the diffing process and the transfer.

This is necessary in tape-world because tapes are a pain to use and have a high 
failure rate.

With a D2D backup you're offloading the failure issue onto a lower level and 
the difference between accessing one file or 10 
files is pretty small- after all you have the index to tell you which one(s) 
will be used to construct it.

I guess my question to you is, what is the problem you hope this will solve?

- Serge