[Techtalk] ide problem?

[Chris Wilson]

Hi Maria,

On Tue, 3 Feb 2009, Maria Pinjanainen wrote:

> The md4 has this troubles. At least the smartd tells it.
>
> Device: /dev/hda, 2 Currently unreadable (pending) sectors
> Device: /dev/hda, 2 Offline uncorrectable sectors
>
> From the syslog. Etch start the cron and make it nice until the last 
> arrays. It ends to kernel panic.
>
> The md4 device is only a data device. So, why it is going to kill whole 
> system? Or is there any other hardware or software trouble?

It should not actually panic and crash the whole system. I'd need to see 
the details of the panic to be sure what is happening there.

However, the disk is busy trying to access the bad sector. This means 
that it cannot do anything else, e.g. read other parts of the disk that 
might be required for normal operation, while this is happening. Some 
disks will try for a very long time before giving up. Linux is probably 
also retrying the reads which makes it worse.

What is /dev/md4 for? Is it a swap partition? That could cause the system 
to crash if there are bugs in the RAID driver and it stops answering 
requests. I'd recommend against using swap on RAID.

I would recommend replacing the hard disk, however it MIGHT be possible to 
prolong its life by manually rewriting the bad sectors. To do this, remove 
it from /dev/md4 and add it back again. Otherwise, I'd recommend that you 
remove it until you can replace the hard disk.

I would not disable checkarray, as it protects you from much more serious 
problems where you have undetected or unrepaired bad or unreadable sectors 
in both drives and therefore cannot recover the array after a disk 
failure.

Cheers, Chris.
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