From: Lars Wirzenius <liw@liw.fi>
To: Josef Bacik <josef@redhat.com>
Cc: Gordan Bobic <gordan@bobich.net>,
BTRFS MAILING LIST <linux-btrfs@vger.kernel.org>
Subject: Re: Offline Deduplication for Btrfs
Date: Wed, 05 Jan 2011 19:58:13 +0000 [thread overview]
Message-ID: <1294257493.2953.33.camel@havelock.lan> (raw)
In-Reply-To: <20110105194645.GC2562@localhost.localdomain>
On ke, 2011-01-05 at 14:46 -0500, Josef Bacik wrote:
> Blah blah blah, I'm not having an argument about which is better because I
> simply do not care. I think dedup is silly to begin with, and online dedup even
> sillier. The only reason I did offline dedup was because I was just toying
> around with a simple userspace app to see exactly how much I would save if I did
> dedup on my normal system, and with 107 gigabytes in use, I'd save 300
> megabytes. I'll say that again, with 107 gigabytes in use, I'd save 300
> megabytes. So in the normal user case dedup would have been wholey useless to
> me.
I have been thinking a lot about de-duplication for a backup application
I am writing. I wrote a little script to figure out how much it would
save me. For my laptop home directory, about 100 GiB of data, it was a
couple of percent, depending a bit on the size of the chunks. With 4 KiB
chunks, I would save about two gigabytes. (That's assuming no MD5 hash
collisions.) I don't have VM images, but I do have a fair bit of saved
e-mail. So, for backups, I concluded it was worth it to provide an
option to do this. I have no opinion on whether it is worthwhile to do
in btrfs.
(For my script, see find-duplicate-chunks in
http://code.liw.fi/debian/pool/main/o/obnam/obnam_0.14.tar.gz or get the
current code using "bzr get http://code.liw.fi/obnam/bzr/trunk/".
http://braawi.org/obnam/ is the home page of the backup app.)
--
Blog/wiki/website hosting with ikiwiki (free for free software):
http://www.branchable.com/
next prev parent reply other threads:[~2011-01-05 19:58 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-05 16:36 Offline Deduplication for Btrfs Josef Bacik
2011-01-05 16:36 ` [PATCH] Btrfs: add extent-same ioctl for dedup Josef Bacik
2011-01-05 17:50 ` Simon Farnsworth
2011-01-05 16:36 ` [PATCH] Btrfs-progs: add dedup functionality Josef Bacik
2011-01-05 17:42 ` Offline Deduplication for Btrfs Gordan Bobic
2011-01-05 18:41 ` Diego Calleja
2011-01-05 19:01 ` Ray Van Dolson
2011-01-05 20:27 ` Gordan Bobic
2011-01-05 20:28 ` Josef Bacik
2011-01-05 20:25 ` Gordan Bobic
2011-01-05 21:14 ` Diego Calleja
2011-01-05 21:21 ` Gordan Bobic
2011-01-05 19:46 ` Josef Bacik
2011-01-05 19:58 ` Lars Wirzenius [this message]
2011-01-05 20:15 ` Josef Bacik
2011-01-05 20:34 ` Freddie Cash
2011-01-05 21:07 ` Lars Wirzenius
2011-01-05 20:12 ` Freddie Cash
2011-01-05 20:46 ` Gordan Bobic
[not found] ` <4D250B3C.6010708@shiftmail.org>
2011-01-06 1:03 ` Gordan Bobic
2011-01-06 1:56 ` Spelic
2011-01-06 10:39 ` Gordan Bobic
2011-01-06 3:33 ` Freddie Cash
2011-01-06 1:19 ` Spelic
2011-01-06 3:58 ` Peter A
2011-01-06 10:48 ` Gordan Bobic
2011-01-06 13:33 ` Peter A
2011-01-06 14:00 ` Gordan Bobic
2011-01-06 14:52 ` Peter A
2011-01-06 15:07 ` Gordan Bobic
2011-01-06 16:11 ` Peter A
2011-01-06 18:35 ` Chris Mason
2011-01-08 0:27 ` Peter A
2011-01-06 14:30 ` Tomasz Torcz
2011-01-06 14:49 ` Gordan Bobic
2011-01-06 1:29 ` Chris Mason
2011-01-06 10:33 ` Gordan Bobic
2011-01-10 15:28 ` Ric Wheeler
2011-01-10 15:37 ` Josef Bacik
2011-01-10 15:39 ` Chris Mason
2011-01-10 15:43 ` Josef Bacik
2011-01-06 12:18 ` Simon Farnsworth
2011-01-06 12:29 ` Gordan Bobic
2011-01-06 13:30 ` Simon Farnsworth
2011-01-06 14:20 ` Ondřej Bílka
2011-01-06 14:41 ` Gordan Bobic
2011-01-06 15:37 ` Ondřej Bílka
2011-01-06 8:25 ` Yan, Zheng
-- strict thread matches above, loose matches on Subject: below --
2011-01-06 9:37 Tomasz Chmielewski
2011-01-06 9:51 ` Mike Hommey
2011-01-06 16:57 ` Hubert Kario
2011-01-06 10:52 ` Gordan Bobic
2011-01-16 0:18 Arjen Nienhuis
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