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Re: [LUG] Combining two drives into one

 

On 21/10/10 22:34, Gordon Henderson wrote:
On Thu, 21 Oct 2010, Rob Beard wrote:

Hi folks,

I've got an interesting one for you...

Basically I have an external USB hard drive which takes multiple
drives. It has 2 x 500GB SATA drives giving 1TB. Now the controller in
the case has got a broken SATA connector so I can currently only
connect one drive.

However, I have a feeling there's some important data on there which
needs recovering.

So I'm trying to figure out how to get the data off. If I put one
drive in a PC it comes up with the partition table and I can mount it.
If I put the other drive in a PC it comes up as blank (presumably
because it's not got a partition table on it). I think it must use
something like concatenation.

My first thought was to dd one drive, then the other and combine the
two image files however I don't have a big enough drive. So I wondered
if I might be able to cheat and combine the two devices (in this case
sdc and sdd) into a new device (say sde) so I can retrieve anything
important off the drives?

How much data did you have on the pair?


About 900GB, there was 1TB in total. As far as I know there is only so much data (maybe a couple of hundred gig) that I want to get back, the rest is backups of my laptop which I've restored but not deleted.

I'd be surprised if the controller was clever enough to do anything
other than dumb
concatenation...


That's what I was thinking.

You might want to try

mdadm -A /dev/md1 --level=linear /dev/sdd /dev/sde

and see what happens... if it doesn't complain, then try:

fsck -fC -n /dev/md1

and if that doesn't complain, then you're won - maybe.


Ahh great, I'll give that a try this weekend (most probably Sunday). Just got to wait until the wife is out so I can borrow her PC (it's the only machine I have handy with enough SATA ports).

If the mdadm fails, then you might try --level=stripe however I suspect
that's unlikely and
you'll need to know the chunk size too.


Okay.

If the total data-set was under 500GB you might find it's all on the
first disk too, however...


Yeah, I think it'll probably be on both disks. I'll give it a try, I'm assuming I can mount it read only anyway just in case.

Rob

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