From: "Stephen C. Tweedie" <sct@redhat.com>
To: "Stephen C. Tweedie" <sct@redhat.com>,
Neil Brown <neilb@cse.unsw.edu.au>,
linux-kernel@vger.kernel.org
Subject: Re: Thoughts on using fs/jbd from drivers/md
Date: Sat, 18 May 2002 13:47:50 +0100 [thread overview]
Message-ID: <20020518134750.B2594@redhat.com> (raw)
In-Reply-To: <15587.18828.934431.941516@notabene.cse.unsw.edu.au> <20020516161749.D2410@redhat.com> <20020517182942.GF627@matchmail.com> <20020517193410.W2693@redhat.com> <20020518013537.GH627@matchmail.com>
Hi,
On Fri, May 17, 2002 at 06:35:37PM -0700, Mike Fedyk wrote:
> On Fri, May 17, 2002 at 07:34:10PM +0100, Stephen C. Tweedie wrote:
> > Degraded mode relies on the parity disk being in sync at all times ---
>
> Doesn't degraded mode imply that there are not any parity
> disk(raid4)/stripe(raid5) updates?
Nope, partity updates still occur. It's more expensive than in
non-degraded mode, but parity still gets updated. If it wasn't, you
would not be able to write to a degraded array at all, as updating
parity is the only way that you can write to a block which maps to a
failed disk. By using parity, we only ever fail requests if there are
two or more failed disks in the array.
Cheers,
Stephen
next prev parent reply other threads:[~2002-05-18 12:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-16 5:54 Thoughts on using fs/jbd from drivers/md Neil Brown
2002-05-16 15:17 ` Stephen C. Tweedie
2002-05-17 18:29 ` Mike Fedyk
2002-05-17 18:34 ` Stephen C. Tweedie
2002-05-18 1:35 ` Mike Fedyk
2002-05-18 12:47 ` Stephen C. Tweedie [this message]
2002-05-21 9:03 ` Helge Hafting
2002-05-26 8:41 ` Daniel Phillips
2002-05-27 11:34 ` Stephen C. Tweedie
2002-05-27 11:50 Neil Brown
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