From: Neil Brown <neilb@cse.unsw.edu.au>
To: Mike Fedyk <mfedyk@matchmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Define conflict between ext3 and raid patches against 2.2.19
Date: Thu, 20 Sep 2001 08:35:04 +1000 (EST) [thread overview]
Message-ID: <15273.7576.395258.345452@notabene.cse.unsw.edu.au> (raw)
In-Reply-To: message from Mike Fedyk on Wednesday September 19
In-Reply-To: <20010916155835.C24067@mikef-linux.matchmail.com> <15271.11056.810538.66237@notabene.cse.unsw.edu.au> <20010919133811.B22773@mikef-linux.matchmail.com>
On Wednesday September 19, mfedyk@matchmail.com wrote:
> On Tue, Sep 18, 2001 at 09:08:32PM +1000, Neil Brown wrote:
> >
> > You should be aware that ext3 (and other journalling filesystems) do
> > not work reliably over RAID1 or RAID5 in 2.2. Inparticular, you can
> > get problems when the array is rebuilding/resyncing.
> >
> > But if you only plan to use ext3 with raid0 or linear, you should be
> > fine.
> >
>
> Can you point me to an archive that describes how to trigger this bug?
>
> Was it in linux-raid or ext3-users or ...?
>
> Mike
I don't remember exactly where or when I read it - either linux-raid
or linux-kernel. It was asserted by Stephen Tweedie.
The problem is that ext3 is very careful about when it writes buffer
to disk : it won't release a buffer until the relevant journal entry
is committed.
However when a RAID rebuild happens, every block on the array is read
into the buffer cache (if it isn't already there) and then written
back out again. This defeats the control that ext3 tries to maintain
on the buffer cache.
I don't know exactly what large-scale effects this might have. It
could be simply that a crash at the wrong time could leave the
filesystem corrupted. But I heard of one person who claimed to get
filesystem corruption after using reiserfs over RAID1 in 2.2, so maybe
it's worse than that.
If you really need to know, I suggest you ask on ext3-users.
NeilBrown
next prev parent reply other threads:[~2001-09-19 22:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-09-16 22:58 Define conflict between ext3 and raid patches against 2.2.19 Mike Fedyk
2001-09-16 23:09 ` Lehmann
2001-09-17 1:43 ` Mike Fedyk
2001-09-17 4:42 ` Andreas Dilger
2001-09-18 11:08 ` Neil Brown
2001-09-18 19:24 ` Mike Fedyk
2001-09-19 20:38 ` Mike Fedyk
2001-09-19 22:35 ` Neil Brown [this message]
2001-09-21 13:10 ` Stephen C. Tweedie
2001-09-21 22:44 ` Mike Fedyk
2001-10-01 21:17 ` Hans Reiser
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=15273.7576.395258.345452@notabene.cse.unsw.edu.au \
--to=neilb@cse.unsw.edu.au \
--cc=linux-kernel@vger.kernel.org \
--cc=mfedyk@matchmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).