Re: Driver retries disk errors.

[Robert Hancock <hancockr@shaw.ca>]

Quite likely, in that case the drive has exhausted its spare pool, and there 
are a bunch of bad sectors that have already been reallocated. Some drives 
will reallocate sectors if they are still readable but the sector appears to 
be marginal.


----- Original Message ----- 
From: "Rogier Wolff" <R.E.Wolff@harddisk-recovery.nl>
Newsgroups: fa.linux.kernel
To: "Theodore Ts'o" <tytso@mit.edu>; <linux-kernel@vger.kernel.org>; 
<linux-ide@vger.kernel.org>
Sent: Monday, August 30, 2004 4:19 PM
Subject: Re: Driver retries disk errors.


> On Mon, Aug 30, 2004 at 01:46:32PM -0400, Theodore Ts'o wrote:
>> > a filesystem: if we recover one block this way, the next block will be
>> > errorred and the filesystem "crashes" anyway. In fact this behaviour
>> > may masquerade the first warnings that something is going wrong....
>>
>> If the block gets successfully read after 2 or 3 tries, it might be a
>> good idea for the kernel to automatically do a forced rewrite of the
>> block, which should cause the disk to do its own disk block
>> sparing/reassignment.
>
> Hi Ted,
>
> I agree that this is the theory. In practise however, I've never
> seen it work correctly. We've seen several disks with say 1-5 bad
> blocks and nothing else, and "dd if=/dev/zero of=/dev/<disk>" doesn't
> seem to cure them.
>
> Roger.
>
> -- 
> +-- Rogier Wolff -- www.harddisk-recovery.nl -- 0800 220 20 20 --
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