[CentOS] Deduplicated archives via hardlinks [Was: XFS or EXT3 ?]
Adam Tauno Williams
awilliam at whitemice.org
Fri Dec 3 21:14:21 UTC 2010
On Fri, 2010-12-03 at 12:51 -0800, John R Pierce wrote:
> On 12/03/10 12:25 PM, Les Mikesell wrote:
> > Whenever anyone mentions backups, I like to plug the backuppc program
> > (http://backuppc.sourceforge.net/index.html and packaged in EPEL). It
> > uses compression and hardlinks all duplicate files to keep much more
> > history than you'd expect on line with a nice web interface - and does
> > pretty much everything automatically.
> I'm curious how you backup backuppc, like for disaster recovery,
I know nothing about backuppc; I don't use it. But we use rsync with
the same concept for a deduplicated archive.
> archival, etc? since all the files are in a giant mess of symlinks
No, they are not symbolic links - they are *hard links*. That they are
hard-links is the actual magic. Symbolic links would provide the
automatic deallocation of expires files.
> (for deduplication) with versioning, I'd have to assume the archive
> volume gets really messy after awhile, and further, something like that
> is pretty darn hard to make a replica of it.
I don't see why; only the archive is deduplicated in this manner, and
it certainly isn't "messy". One simply makes a backup [for us that
means to tape - a disk is not a backup] of the most current snapshot.
The script just looks like -
export ROOT="/srv/cifs/Arabis-Red"
export STAMP=`date +%Y%m%d%H`
export LASTSTAMP=`cat $ROOT/LAST.STAMP`
mkdir $ROOT/$STAMP
mkdir $ROOT/$STAMP/home
nice rsync --verbose --archive --delete --acls \
--link-dest $ROOT/$LASTSTAMP/home/ \
--numeric-ids \
-e ssh \
archivist at arabis-red:/home/ \
$ROOT/$STAMP/home/ \
2>&1 > $ROOT/$STAMP/home.log
echo $STAMP > $ROOT/LAST.STAMP
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