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Date: Sat, 19 Jan 2008 15:53:17 +0100 From: Pavel Machek <pavel@....cz> To: "linux-os (Dick Johnson)" <linux-os@...logic.com> Cc: Theodore Tso <tytso@....EDU>, Bryan Henderson <hbryan@...ibm.com>, Ric Wheeler <ric@....com>, Al Boldi <a1426z@...ab.com>, Alan Cox <alan@...rguk.ukuu.org.uk>, David Chinner <dgc@....com>, linux-kernel@...r.kernel.org, Daniel Phillips <phillips@...gle.com>, Rik van Riel <riel@...hat.com>, Valerie Henson <val.henson@...il.com> Subject: Re: [Patch] document ext3 requirements (was Re: [RFD] Incrementalfsck) On Fri 2008-01-18 10:16:30, linux-os (Dick Johnson) wrote: > > On Fri, 18 Jan 2008, Theodore Tso wrote: > > > On Thu, Jan 17, 2008 at 04:31:48PM -0800, Bryan Henderson wrote: > >> But I heard some years ago from a disk drive engineer that that is a myth > >> just like the rotational energy thing. I added that to the discussion, > >> but admitted that I haven't actually seen a disk drive write a partial > >> sector. > > > > Well, it would be impossible or at least very hard to see that in > > practice, right? My understanding is that drives do sector-level > > checksums, so if there was a partially written sector, the checksum > > would be bogus and the drive would return an error when you tried to > > read from it. > > > >> Ted brought up the separate issue of the host sending garbage to the disk > >> device because its own power is failing at the same time, which makes the > >> integrity at the disk level moot (or even undesirable, as you'd rather > >> write a bad sector than a good one with the wrong data). > > > > Yep, exactly. It would be interesting to see if this happens on > > modern hardware; all of the evidence I've had for this is years old at > > this point. > > I have a Seagate Barracuda 7200.9 80 Gbyte SATA drive that I > use for experiments. I can permanently destroy a EXT3 file-system > at least 50% of the time by disconnecting the data cable while > a `dd` write to a file is in progress. Something bad happens > making partition information invalid. I have to re-partition > to reuse the drive. Does turning off writeback cache on disk help? This is quite serious, I'd say... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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