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Re: Question on backups using rsync



On Mon, Dec 19, 2005 at 08:01:04PM -0700, Daniel Webb wrote:

> One thing to consider is that it's safer to use a LVM snapshot while
> copying a mirror.  That way it won't matter if the files change during the
> mirroring.  This issue won't keep the system from booting, since libc6 and
> such never change, but if a database file changes, for example, it could wreck
> havoc with that.

<replying to myself here>

I read somewhere that this isn't a problem with rsync, that it only copies
atomically.  So are snapshots even needed if using rsync?  I couldn't find
anything about this issue on the man page, but it is a huge man page.  Also
couldn't find anything about this issue in the rdiff-backup man page.

Another question:

I'm curious as to the relative merits of rdiff-backup vs. rsync snapshots
(http://www.mikerubel.org/computers/rsync_snapshots/).  Am I mistaken in
thinking that the rsync snapshots method would be very inefficient if a small
part of a large file (like revision control databases) changed regularly?  How
much overhead is involved in all those hardlinks compared to rdiff-backup's
metadata overhead?



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