[Sussex] Anybody out there any good at rescuing hard drives?

[Steve Dobson]

Dominic

On Wed, Feb 08, 2006 at 09:29:46AM +0000, Dave Chapman wrote:
> On Sunday 05 February 2006 17:40, Dominic Humphries wrote:
> > Evening all,
> >
> > my SATA hard drive has died :(
> >
> > The basic sequence of events was:
> >
> >    Tried to mount IDE disk: "mount /dev/hda1 /mnt"
> >
> >    xterm locked up
> >
> >    Killed xterm
> >
> >    started new xterm
> >
> >    PC locked up
> >
> >    Rebooted PC
> >
> >    Nothing works
> >
> > That pretty much sums it up.

This suggests to me that when you do a read/write operation to the
disk (and mount(1) is doing read/writes to the disk) then the kernel
sends the read/write request but the disk doesn't respond.  IIRC when
the kernel performs IO like this it puts the process (the mount command)
into an uniterruptible sleep state waiting for the IO request to complete.

You can use ps(1) to see if this is the case.

Have you tried mounting the disk in read only mode.  If it is just the
writes that are the problem then using read only mode will allow you
to back the data up.

<snip>
> > And fsck doesn't help either
> >
> >    fsck 1.38-WIP (09-May-2005)
> >    e2fsck 1.38-WIP (09-May-2005)
> >    Couldn't find ext2 superblock, trying backup blocks...
> >    fsck.ext2: Bad magic number in super-block while trying to open /dev/sda
> >
> >    The superblock could not be read or does not describe a correct ext2
> >    filesystem.  If the device is valid and it really contains an ext2
> >    filesystem (and not swap or ufs or something else), then the superblock
> >    is corrupt, and you might try running e2fsck with an alternate
> > superblock: e2fsck -b 8193 <device>

When you create the ext2/3 partition did to take a not of the super blocks
it reported?  Some distos hide this from you (in the name of a clean GUI
I guess) but when a disk dies that information is kinda useful.

> > There should be half a dozen ext3 partitions found on this disk. I do have
> > some backups, but they're quite old and I'd be much happier if I could
> > recover the data off my hard drive. But right now, all I have is Knoppix.

Backups won't help here as they do not contain the partition information.
(Unless you were backing up the whole disk using dd(1) or something simular).

> Does the disc make any noise.
> If it is ticking it's the head stuck.
> Try shaking it. As a last resort take the lid off and move the arm  with some 
> thing. A pen would do.
> As I say that's a last resort.

This really is the last resort.  This should be done in clean room conditions,
and there is no way you can get your office or home to those conditions.

Hard disk heads are designed to float of a thin layour of air just above the
surface of the platter.  The gap between the heads and the platter surface
is very, very, very small.  A partical of smoke is much bigger.  As a result 
should a comtaminate in the air get between the disk head and the surface
then either it will scrape the magnetic sufrace from the platter - erasing
your data for all time, or it will move the head far enought away from the
surface that it can no longer read the data.

I do not recomend Dave's advice.

Steve
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
Url : http://mailman.lug.org.uk/pipermail/sussex/attachments/20060208/ecb02db4/attachment.pgp