linux-kernel - Re: tools support for non-512 byte sector sizes

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Message-ID: <20080809132144.GB13169@ucw.cz>
Date:	Sat, 9 Aug 2008 15:21:44 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Matt Domsch <Matt_Domsch@...l.com>
Cc:	Jim Meyering <jim@...ering.net>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Matthew Wilcox <matthew@....cx>,
	Ric Wheeler <rwheeler@...hat.com>, linux-scsi@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jeff Garzik <jeff@...zik.org>
Subject: Re: tools support for non-512 byte sector sizes

Hi!

> >   - some disk makers have sort of agreed not to do that, and
> >       expect forever to hide the larger underlying sector size
> >       behind a virtual 512 (of course, this imposes alignment
> >       restrictions, but that's a smaller problem)
> 
> yes, this is happening also.
> 
> There will be 3 types of disks eventually:
> 1) those that report a 512-byte sector size, and are really a 512-byte
>    size.  This is nearly all disks today.
> 
> 2) those that report a 512-byte sector size, but are really a
>    4096-byte size, and the drive does the conversions and
>    read/modify/write.  T10 and T13 are looking to add commands to
>    expose this different underlying physical sector size so the OS
>    could be aware of it.  This is primarily being driven to mitigate
>    any problems that may happen with "legacy" OSs that are not aware
>    of the difference.

How is this going to work with journaling? This has nasty property
that if you are writing to sector n during powerfail, disk may also
kill sectors n-3, n-2 and n-1..... and that's bad right?

							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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