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From: Soeren Schmidt <sos@spider.deepcore.dk>
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To: Martin Blapp <mb@imp.ch>
Date: Wed, 23 Apr 2003 09:21:17 +0200 (CEST)
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cc: freebsd-stable@FreeBSD.ORG
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Subject: Re: Deadlock with ATA disk on FreeBSD 4.8 Stable
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It seems Martin Blapp wrote:
> We encounter here a deadlock with a quite new ATA 120GB disk.
> The disk worked good for about 3 weeks, but now we have a strange
> problem.
> 
> There seems to be one defective file on the disk. fsck doesn't find
> it, and if I do a
> 
> cat file > /dev/null
> 
> The machine locks completly. Serial console is dead, no remote DDB
> via ALTBREAK possible anymore, no panic message, just freezed.
> 
> The evil began after we installed this ATA disk. It only happens for
> one file on this disk, the other 10000 files are fine.
> 
> Do you have a idea why break into the debugger doesn't work anymore ?
> Even if we have a hard-error on the disk, this should still work,
> shouln't it ?

One thing that could explain this is that the disk stops working in the
midst of a busmaster DMA transfer, that will effectively lockup the
system in most cases. I'm suspecting bad HW here, as it makes no sense
you can access the rest of the disk without problems.. If you can spare
the data, I'd do a dd if=/dev/zero of=/dev/adN bs=1m and try to get the
disk to remap all bad sectors...

-Søren