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Re: Advise on backing up files in Etch.



On Mon, May 14, 2007 at 02:08:56PM +0200, Dan H wrote:
> On Sun, 13 May 2007 20:56:21 -0400
> Roberto C. Sánchez <roberto@connexer.com> wrote:
> 
> > Good point.  What I like about the rsync snapshots is that I can
> > "browse" back in time.  In my case, I always have hourly snapshots
> > going back four hours, daily snapshots going back four days and weekly
> > snapshots going back four weeks.  That works out rather nicely in that
> > it is trivial for me to compare files across snapshots.
> 
> That sounds nice but how does it work? I only use rsync to keep exact
> mirrors of directory trees in sync, but have never heard about the
> history thingy.
> 
If you read "Easy Automated Snapshot-Style Backupse with Rsync" [0],
it will walk you through the process of setting up rsync to use
hardlinks to create the snapshots.  That is, you have a "master" backup,
which is always the most recent (one of the tweaks that I made was to
use systemimager instead of raw rsync to create that image).  You then
use rsync to create hardlinks in such a way that only the changed files
take up additional space.  For example, with a server that has about 5
GB of space used up (it is a small machine), I can backup the four
hourly, four daily and four weekly snapshots in a total of about 10 GB
(instead of the 60 GB that would be required if every image were created
fresh each time).  That also means that only the first image takes a
long time to create.  After that, the other images are only the
differences between the current state and the most recent image.

Regards,

-Roberto

[0] http://www.mikerubel.org/computers/rsync_snapshots/

-- 
Roberto C. Sánchez
http://people.connexer.com/~roberto
http://www.connexer.com

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