Hello again,
i have probably found an intersting solution for doing rdiff-
backups via rsync with local mirror and without needing twice the
space as usual.
i`d like to discuss this solution and getting some feedback.
if it`s a good and reliable solution, maybe it`s useful for others,
too.
the trick for saving the diskspace for rsync mirror is using the
rsync option "--link-dest",whis is set to the rdiff-backup
repositroy. --link-dest means, that rsync can store data space-
efficiently by creating hardlinks. hardlinks are created whenever
the rsynced file already is at another destination. so if the rdiff-
backup directory contains exactly the same file which is being
rsynced, then rsync can detect this and create a hardlink instead.
files which changed or which are new are just rsynced as usual. for
me this saves most of the space the rsync directory normally needs.
this is my current backup script (i simplified it just to show the
essential) :
------------
cd /backup
rm -rf hostA_rsync
mkdir hostA_rsync
rsync -az -H --link-dest=./hostA_rdiff hostA:/ ./hostA_rsync
rdiff-backup --no-hard-links ./hostA_rsync ./hostA_rdiff
------------
for my curiousity i needed to add --no-hard-links to rdiff-backup,
otherwise rdiff-backup behaved strange with this.
see the difference:
before:
du -s -k hostA*
30014511 hostA_rdiff
24219719 hostA_rsync
after (made a second hostA_rdiff for testing - this is why it is
smaller):
du -s -k hostA*
24243554 hostA_rdiff
219719 hostA_rsync
since i just have found this solution and didnŽt test in depth
(maybe there are problems?) , i`d glad to hear some comments about
this.
regards
roland
------------------------------------------
Betreff: Re: [rdiff-backup-users] rdiff-backup vs. rsync
(d) at the remote end
Von: "roland" <address@hidden> ins Adressbuch
An: "Gerard van Dijnsen" <address@hidden>
Cc: address@hidden
Datum: 24.06.06 16:03:31
hi!
mhhh - still wondering here and spending thoughts over and over
again...
As far as I can see, there are a lot of reasons for using a server on
the receiving side.
yes - but why does this need rdiff-backup as server? rsync can run
as a
server, too.
One of them is storage of metadata, the most
important however is keeping a history using 'reverse' diffs.
mhh - but metadata is only stored on the backup-machine within the
rdiff-backup repository.
nothing on the client side. rdiff-backup just pulls the data and
metadata
from the backup client.
whatever data/metadata rdiff-backup needs on the receiving side for
storing
this - an rsync
daemon on the remote site should be able to "deliver" this (imho - in
theory).
does somebody have a clue what's different "on the wire" between
rsync and
rdiff-backup ?
itŽs gets a bigger problem for me, because i cannot install rdiff-
backup on
many remote machines and
so i need to create a local copy via rsync and rdiff-backup'ing it
afterwards.
this doubles storage and isn`t very optimal.
ok, i know that i can convert a rsync mirror with "-b --force" into a
rdiff-backup repository - but
i`m not allowed to rsync afterwards.
Actually, take a look at Duplicity and you will see a nice example
of what
you are looking for.
thanks. maybe , fusessh is also worth looking at....
regards
roland
----- Original Message -----
From: "Gerard van Dijnsen" <address@hidden>
Cc: <address@hidden>
Sent: Saturday, May 27, 2006 6:45 PM
Subject: Re: [rdiff-backup-users] rdiff-backup vs. rsync(d) at the
remote
end
As far as I can see, there are a lot of reasons for using a server on
the receiving side. One of them is storage of metadata, the most
important however is keeping a history using 'reverse' diffs. This
might
be implemented differently using rsync perhaps, I am not sure.
Actually,
take a look at Duplicity and you will see a nice example of what
you are
looking for. You only need ssh on the receiving side for this to
work...
Gerard
On Sat, 2006-05-27 at 13:24 +0200, roland wrote:
Hello !
while thinking about (and digging into) how rdiff-backup is working
internally, i wonder a little bit about rdiff-backup being needed
at the
remote end.
wouldn`t rsync(d) be sufficient for this (in theory) ?
i`m asking this, because it's a lot easier and more "lightweight" to
install
rsync(d) on the clients you need to backup.
regarding "what's being transferred over the wire or being done
at the
remote end" - can someone explain the difference between rdiff-
backup and
rsync and give a comment about possible replacement of rdiff-
backup with
rsync(d) ?
regards
roland
ps:
actually, i even have one machine i need to rsync first to a local
directory
and rdiff-backup from that, because i'm not allowed to install
python on
that machine. so this takes twice the space on my backup machine.
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