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Date: Mon, 28 Nov 2011 02:54:51 -0500
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] libxfs: Get Physical Sector Size instead of Logical
	Sector size
Message-ID: <20111128075451.GA6000@infradead.org>
References: <1322162451-17036-1-git-send-email-cmaiolino@redhat.com>
	<20111124195042.GA3671@andromeda.usersys.redhat.com>
	<20111127010643.GU2386@dastard> <4ED2C233.8010104@sandeen.net>
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To: Eric Sandeen <sandeen@sandeen.net>
Cc: Carlos Maiolino <cmaiolino@redhat.com>, xfs@oss.sgi.com

On Sun, Nov 27, 2011 at 05:05:23PM -0600, Eric Sandeen wrote:
> > i.e. do we have any guarantee at all that a PBS sized IO will either
> > wholly complete or wholly fail when PBS != sector size? And if not,
> > why is this a change we should make given it appears to me to
> > violate a fundamental assumption of the filesystem design?
> 
> I had the expectation that physical block size WAS the fundamental/atomic
> IO size for the disk, and anything smaller required read/modify/write.
> So I made this suggestion (and I think hch concurred) so that we weren't
> doing log IOs which required RMW & translation.

Yes, that is how it is defined. 

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