Block device layer freezing block device access ?

From: Dag Wieers
Date: Sun Jun 19 2005 - 19:18:50 EST


I've got an (apparently) broken disk. But I see the following behaviour.
The kernel reads the partition table without problems and then has some
unrecoverable errors.

After the system has booted, the disk has become inaccessible, but it
appears that the driver/block device layer has decided to make the disk
inaccessible, as I can't even access the partition table anymore (which
was previously accessible during boot).

So I was wondering if there is a mechanism (probably in the block device
layer, as I see it with 2 different sata chipsets) that decides to declare
the disk 'dead' ?

The reason I am asking is that if this is true, I'd like to disable
that to recover whatever is still readable from the disk. And it would
seem to make more sense to make the media read-only (which is what it
normally does for filesystems after unrecoverable errors iirc) instead of
freezing the block device layer.

PS the disk is not being accessed or mounted at bootup, I'm booting from a
rescue image. So the only access (I think) is happening is reading the
partition table.

PS2 I've looked at the kernel-parameters file, but I think it is out-dated
so no option being in there probably doesn't mean it's not impossible.

PS3 Thanks for reminding me that taking regular backups and using RAID is
a wonderful thing, unfortunately that doesn't help me now, does it ? :) I
have an older backup anyway, but would prefer to recover whatever is

Thanks in advance for your help.

Kind regards,
-- dag wieers, dag@xxxxxxxxxx, --
[all I want is a warm bed and a kind word and unlimited power]
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