From: Calvin Walton <calvin.walton@kepstin.ca>
To: "Fajar A. Nugraha" <list@fajar.net>
Cc: "Brian J. Murrell" <brian@interlinx.bc.ca>, linux-btrfs@vger.kernel.org
Subject: Re: efficiency of btrfs cow
Date: Sun, 06 Mar 2011 11:17:26 -0500 [thread overview]
Message-ID: <1299428248.15017.13.camel@ayu> (raw)
In-Reply-To: <AANLkTi=-bxNwFmp8GZ_Foz=CSP2kUOwqPKAaMFapGuz+@mail.gmail.com>
On Sun, 2011-03-06 at 23:02 +0700, Fajar A. Nugraha wrote:
> On Sun, Mar 6, 2011 at 10:46 PM, Brian J. Murrell <brian@interlinx.bc.ca> wrote:
> > # cp -al /backup/previous-backup/ /backup/current-backup
> > # rsync -aAHX ... --exclude /backup / /backup/current-backup
> >
> > The shortcoming of this of course is that it just takes 1 byte in a
> > (possibly huge) file to require that the whole file be recopied to the
> > backup.
>
> If you have snapshots anyway, why not :
> - create a snapshot before each backup run
> - use the same directory (e.g. just /backup), no need to "cp" anything
> - add "--inplace" to rsync
To add a bit to this: if you *do not* use the --inplace option on rsync,
rsync will rewrite the entire file, instead of updating the existing
file!
This of course negates some of the benefits of btrfs's COW support when
doing incremental backups.
--
Calvin Walton <calvin.walton@kepstin.ca>
next prev parent reply other threads:[~2011-03-06 16:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-06 15:46 efficiency of btrfs cow Brian J. Murrell
2011-03-06 16:02 ` Fajar A. Nugraha
2011-03-06 16:11 ` Brian J. Murrell
2011-03-06 16:17 ` Calvin Walton [this message]
2011-03-06 16:18 ` Brian J. Murrell
2011-03-06 17:22 ` Freddie Cash
2011-03-06 16:06 ` Calvin Walton
2011-03-06 16:17 ` Brian J. Murrell
2011-03-23 12:39 ` Brian J. Murrell
2011-03-23 15:53 ` Chester
2011-03-23 16:19 ` Brian J. Murrell
2011-03-23 17:36 ` Kolja Dummann
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