Bad sector on drive ...

[John Nielsen]

On Saturday 10 February 2007 09:47, Marc G. Fournier wrote:
> --On Saturday, February 10, 2007 01:00:21 -0600 Dan Nelson
>
> <dnelson at allantgroup.com> wrote:
> > In the last episode (Feb 10), Marc G. Fournier said:
> >> Short of a reformat, any way of marking the following as bad? :(
> >>
> >> Feb 10 02:27:20 ganymede kernel: ad4: FAILURE - READ_DMA
> >> status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE> LBA=176887263 Feb
> >> 10 02:27:25 ganymede kernel: ad4: TIMEOUT - READ_DMA retrying (1 retry
> >>  left) LBA=176887324 Feb 10 02:27:30 ganymede kernel: ad4: TIMEOUT -
> >> READ_DMA retrying (0 retries  left) LBA=176887324 Feb 10 02:27:35
> >> ganymede kernel: ad4: FAILURE - READ_DMA timed out LBA=176887324
> >
> > Try writing to the block causing the error, using dd and the seek=
> > option; if the write succeeds, you're done (and the drive will have
> > either reused the block or reassigned it to a spare). 176887324 If it
> > doesn't succeed, copy what you can off the drive and toss it, since all
> > its spares are used up.
> >
> > I think LBA numbers map directly to seek= values assuming you keep
> > bs=512 and access /dev/ad4 .  I'd try reading the bad block with dd to
> > verify it's the right one before doing a write, though.
>
> 'k, how do you use dd to write to a specific sector?
>
> 	dd of=/dev/ad4 seek=176887324 bs=512 if=/dev/null

dd of=/dev/ad4 seek=176887324 bs=512 count=1 if=/dev/zero

JN