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Date:      Thu, 24 Oct 2002 22:18:33 +0200
From:      Andreas Ntaflos <ant@overclockers.at>
To:        Matthew Reimer <mreimer@vpop.net>
Cc:        freebsd-questions@freebsd.org, freebsd-stable@freebsd.org, kris@obscurity.org
Subject:   Re: fsck lasting several hours (and then forever) after crash
Message-ID:  <20021024201833.GA259@Deadcell.ant>
In-Reply-To: <3DB8228B.90203@vpop.net>
References:  <lists.freebsd.stable.20021024152331.GA43887@xor.obsecurity.org> <lists.freebsd.stable.20021024161227.GA248@Deadcell.ant> <3DB8228B.90203@vpop.net>

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On Thu, Oct 24, 2002 at 11:40:43AM -0500, Matthew Reimer wrote:
> Andreas Ntaflos wrote:
> 
> >Is there anything else I could do to help solving this problem?
> >regards
> 
> We had a problem like this when an ATA disk went bad--the kernel would 
> seem to hang while trying to read the bad part of the disk. Try booting 
> into single-user mode (boot -s) and then try reading all the disk's 
> blocks. If it hangs doing this, then you know it's not fsck's fault:
> 
>     dd if=/dev/ad0s1c of=/dev/null bs=64k
> 

Now that is a good idear! Thanks. I dropped to single user mode and did 
dd if=/dev/ad4s1h of=/dev/null bs=64k. It appears that fsck is not the problem
but my disk is going bad.

> It turned out that our disk just needed a low-level format. Apparently, 
> writing zeroes to (some) disks effects a low-level format, so I zeroed 
> the entire bad disk (dd if=/dev/zero of=/dev/ad0s1c) and then I could 
> read all the disks's blocks without problems. Of course zeroing the disk 
> will destroy all your data. If you knew which blocks were bad you could 
> try zeroing just those blocks; if they weren't holding real important 
> information (like a superblock) then you might be able to save your files.

I am not sure how to interpret the error message I get:

ad4s1h: hard error reading fsbn 61857135 of 28752640-28752767 (ad4s1 bn
61857135; cn 3850 tn 109 sn 18) status=69 error=40

Does that indicate which blocks are bad? If so, how could I try zeroing out
just those blocks? And if not, is there a way to tell which are the real bad
blocks? 

Sorry for sounding newbie'ish, but I've never dealt with something like that
before, at least not with a bad disk.

thanks and regards
-- 
	Andreas "ant" Ntaflos |	"A cynic is a man who knows the price of
	ant@overclockers.at   |	everything, and the value of nothing."
	Vienna, AUSTRIA	      |				     Oscar Wilde
	

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