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From: Neil Brown <neilb@suse.de>
To: David Chinner <dgc@sgi.com>
Cc: Neil Brown <neilb@suse.de>, Timothy Shimmin <tes@sgi.com>,
	xfs@oss.sgi.com
Subject: Re: XFS and write barriers.
Date: Mon, 26 Mar 2007 10:01:01 +1000	[thread overview]
Message-ID: <17927.3389.655835.610940@notabene.brown> (raw)
In-Reply-To: message from David Chinner on Sunday March 25

On Sunday March 25, dgc@sgi.com wrote:
> On Fri, Mar 23, 2007 at 07:00:46PM +1100, Neil Brown wrote:
> > 
> > Why no barriers on an external log device??? Not important, just
> > curious.
> 
> because we need to synchronize across 2 devices, not one, so issuing
> barriers on an external log device does nothing to order the metadata
> written to the other device...

Right, of course.  Just like over a raid0.

So you must have code to wait for all writes to the main device before
writing the commit block on the journal.   How hard is it to fall-back
to that if the barrier fails?

NeilBrown

  reply	other threads:[~2007-03-26  0:01 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-23  1:26 XFS and write barriers Neil Brown
2007-03-23  5:30 ` David Chinner
2007-03-23  7:49   ` Neil Brown
2007-03-25  4:17     ` David Chinner
2007-03-25 23:21       ` Neil Brown
2007-03-26  3:14         ` David Chinner
2007-03-26  4:27           ` Neil Brown
2007-03-26  9:04             ` David Chinner
2007-03-29 14:56               ` Martin Steigerwald
2007-03-29 15:18                 ` David Chinner
2007-03-29 16:49                   ` Martin Steigerwald
2007-03-23  9:50   ` Christoph Hellwig
2007-03-25  3:51     ` David Chinner
2007-03-25 23:58       ` Neil Brown
2007-03-26  1:11     ` Neil Brown
2007-03-23  6:20 ` Timothy Shimmin
2007-03-23  8:00   ` Neil Brown
2007-03-25  3:19     ` David Chinner
2007-03-26  0:01       ` Neil Brown [this message]
2007-03-26  3:58         ` David Chinner
2007-03-27  3:58       ` Timothy Shimmin

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