From: "Roman V. Shaposhnik" <rvs@sun.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] Changelogs & Patches?
Date: Tue, 20 Jan 2009 14:30:33 -0800 [thread overview]
Message-ID: <1232490633.11686.26.camel@goose.sun.com> (raw)
In-Reply-To: <30fef936405d9216f98c10a5c32b42ea@quanstro.net>
On Tue, 2009-01-20 at 09:19 -0500, erik quanstrom wrote:
> > > in the case of zfs, my claim is that since zfs can reuse blocks, two
> > > vdev backups, each with corruption or missing data in different places
> > > are pretty well useless.
> >
> >
> > Got it. However, I'm still not fully convinced there's a definite edge
> > one way or the other. Don't get me wrong: I'm not trying to defend
> > ZFS (I don't think it needs defending, anyway) but rather I'm trying
> > to test my mental model of how both work.
>
> if you end up rewriting a free block in zfs, there sure is. you
> can't decide which one is correct.
You don't have to "decide". You get use generation # for that.
> > P.S. Oh, and in case of ZFS a damaged vdev will be detected (and
> > possibly re-silvered) under normal working conditions, while
> > fossil might not even notice a corruption.
>
> not true. one of many score checks:
>
> srv/lump.c:103: seterr(EStrange, "lookuplump returned bad score %V not %V", u->score, score);
I don't buy this argument for a simple reason: here's a very
easy example that proves my point:
term% fossil/fossil -f /tmp/fossil.bin
fsys: dialing venti at net!$venti!venti
warning: connecting to venti: Connection refused
term% mount /srv/fossil /n/f
term% cd /n/f/test
term% echo 'this is innocent text' > text.txt
term% cat text.txt
this is innocent text
term% dd -if /dev/cons -of /tmp/fossil.bin -bs 1 -count 8 -oseek 278528 -trunc 0
this WAS
8+0 records in
8+0 records out
term% rm /srv/fossil /srv/fscons
term% fossil/fossil -f /tmp/fossil.bin
fsys: dialing venti at net!$venti!venti
warning: connecting to venti: Connection refused
create /active/adm: file already exists
create /active/adm adm sys d775: create /active/adm: file already exists
create /active/adm/users: file already exists
create /active/adm/users adm sys 664: create /active/adm/users: file already exists
nuser 5 len 84
term% mount /srv/fossil /n/f2
term% cat /n/f2/test/text.txt
this WAS innocent text
term%
Of course, with ZFS, the above corruption would be always
noticed and sometimes (depending on your vdev setup)
even silently fixed.
Thanks,
Roman.
next prev parent reply other threads:[~2009-01-20 22:30 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-22 15:27 Venkatesh Srinivas
2008-12-22 15:29 ` erik quanstrom
2008-12-22 16:41 ` Charles Forsyth
2008-12-25 6:34 ` Roman Shaposhnik
2008-12-25 6:40 ` erik quanstrom
2008-12-26 4:28 ` Roman Shaposhnik
2008-12-26 4:45 ` lucio
2008-12-26 4:57 ` Anthony Sorace
2008-12-26 6:19 ` blstuart
2008-12-27 8:00 ` Roman Shaposhnik
2008-12-27 11:56 ` erik quanstrom
2008-12-30 0:31 ` Roman Shaposhnik
2008-12-30 0:57 ` erik quanstrom
2009-01-05 5:19 ` Roman V. Shaposhnik
2009-01-05 5:28 ` erik quanstrom
2008-12-22 17:03 ` Devon H. O'Dell
2008-12-23 4:31 ` Uriel
2008-12-23 4:46 ` Nathaniel W Filardo
2008-12-25 6:50 ` Roman Shaposhnik
2008-12-25 14:37 ` erik quanstrom
2008-12-26 13:27 ` Charles Forsyth
2008-12-26 13:33 ` Charles Forsyth
2008-12-26 14:27 ` tlaronde
2008-12-26 17:25 ` blstuart
2008-12-26 18:14 ` tlaronde
2008-12-26 18:20 ` erik quanstrom
2008-12-26 18:52 ` tlaronde
2008-12-26 21:44 ` blstuart
2008-12-26 22:04 ` Eris Discordia
2008-12-26 22:30 ` erik quanstrom
2008-12-26 23:00 ` blstuart
2008-12-27 6:04 ` Eris Discordia
2008-12-27 10:36 ` tlaronde
2008-12-27 16:27 ` Eris Discordia
2008-12-29 23:54 ` Roman Shaposhnik
2008-12-30 0:13 ` hiro
2008-12-30 1:07 ` erik quanstrom
2008-12-30 1:48 ` Charles Forsyth
2008-12-30 13:18 ` Uriel
2008-12-30 15:06 ` C H Forsyth
2008-12-30 17:31 ` Uriel
2008-12-31 1:58 ` Noah Evans
2009-01-03 22:03 ` sqweek
2009-01-05 5:05 ` Roman V. Shaposhnik
2009-01-05 5:12 ` erik quanstrom
2009-01-06 5:06 ` Roman Shaposhnik
2009-01-06 13:55 ` erik quanstrom
2009-01-05 5:24 ` andrey mirtchovski
2009-01-06 5:49 ` Roman Shaposhnik
2009-01-06 14:22 ` andrey mirtchovski
2009-01-06 16:19 ` erik quanstrom
2009-01-06 23:23 ` Roman V. Shaposhnik
2009-01-06 23:44 ` erik quanstrom
2009-01-08 0:36 ` Roman V. Shaposhnik
2009-01-08 1:11 ` erik quanstrom
2009-01-20 6:20 ` Roman Shaposhnik
2009-01-20 14:19 ` erik quanstrom
2009-01-20 22:30 ` Roman V. Shaposhnik [this message]
2009-01-20 23:36 ` erik quanstrom
2009-01-21 1:43 ` Roman V. Shaposhnik
2009-01-21 2:02 ` erik quanstrom
2009-01-26 6:28 ` Roman V. Shaposhnik
2009-01-26 13:42 ` erik quanstrom
2009-01-26 16:15 ` Roman V. Shaposhnik
2009-01-26 16:39 ` erik quanstrom
2009-01-27 4:45 ` Roman Shaposhnik
2009-01-21 19:02 ` Uriel
2009-01-21 19:53 ` Steve Simon
2009-01-24 3:15 ` Roman V. Shaposhnik
2009-01-24 3:36 ` erik quanstrom
2009-01-26 6:21 ` Roman V. Shaposhnik
2009-01-26 13:53 ` erik quanstrom
2009-01-26 16:21 ` Roman V. Shaposhnik
2009-01-26 17:37 ` erik quanstrom
2009-01-27 4:51 ` Roman Shaposhnik
2009-01-27 5:44 ` erik quanstrom
2009-01-21 20:01 ` erik quanstrom
2009-01-24 3:19 ` Roman V. Shaposhnik
2009-01-24 3:25 ` erik quanstrom
2009-01-20 6:48 ` Roman Shaposhnik
2009-01-20 14:13 ` erik quanstrom
2009-01-20 16:19 ` Steve Simon
2009-01-20 23:52 ` andrey mirtchovski
2009-01-21 4:49 ` Dave Eckhardt
2009-01-21 6:38 ` Steve Simon
2009-01-21 14:02 ` erik quanstrom
2009-01-26 6:16 ` Roman V. Shaposhnik
2009-01-26 16:22 ` Russ Cox
2009-01-26 19:42 ` Roman V. Shaposhnik
2009-01-26 20:11 ` Steve Simon
2008-12-27 7:40 ` Roman Shaposhnik
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