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Date: Tue, 27 Nov 2001 02:39:24 +0000
From: Pavel Machek <pavel@suse.cz>
To: linux-kernel@vger.kernel.org
Subject: Re: Journaling pointless with today's hard disks?
Message-ID: <20011127023923.A38@toy.ucw.cz>
In-Reply-To: <20011125133020.C1811@emma1.emma.line.org> <20011125150433.CEAE889CAD@pobox.com> <20011125173125.A13119@emma1.emma.line.org>
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Hi!

> > "Power off during write operations may make an incomplete sector which
> > will report hard data error when read. The sector can be recovered by a
> > rewrite operation."
> 
> So the proper defect management would be to simply initialize the broken
> sector once a fsck hits it (still, I've never seen disks develop so many
> bad blocks so quickly as those failed DTLA-307045 drives I had).
> 
> Note, the specifications say that the write cache setting is ignored
> when the drive runs out of spare blocks for reassignment after defects
> (so that the drive can return the error code right away when it cannot
> guarantee the write actually goes to disk).

They should turn off write-back after number-of-spare-block < cache-size,
otherwise they are not safe.
								Pavel
-- 
Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.

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