[TriLUG] Need help with recovering data from a drive

[Joseph Mack NA3T via TriLUG]

On Sat, 4 Apr 2015, Moustapha Barry via TriLUG wrote:

> I would appreciate anybody's help on this. I believe that the boot record
> was damaged and that imaging the drive will allow me to recover the data on
> it. Is there any tool I can use to recover the data on this drive?

as soon as you have a disk with problem, unpower it. You don't want more bad 
sectors if that is the problem. I assume the drive is not dead and not clicking.

If it is just a boot sector problem, make up a usb grub flash key (you should 
always have grub on at least some of your flash keys for when this happens), or 
download a bootable CD (will be called supergrub or something like that).

if it's a dieing disk problem:

boot the machine off the systemrescuecd (this can boot another OS too)

http://www.sysresccd.org/SystemRescueCd_Homepage

assume your bad disk is /dev/sda unmounted

assume you have some other disk to copy the bad disk to, mounted at /mnt

run ddrescue in two steps

ddrescue -n /dev/sda /mnt/sda.rescue /mnt/sda.log

(do not erase /mnt/sda.log)

ddrescue -d r3 /dev/sda /mnt/sda.rescue /mnt/sda.log

by watching the output or reading the log file, you'll know how the rescue went.

you can start messing with the copy (mount it and look inside).

If there's large numbers of missing sectors, put the disk in the freezer. Attach 
power/data cables to it, wrap it in a single paper towel and then in a zip lock 
(with the cables poking out of the corner) and put it in the freezer for an hour 
or two. Pull the bag out and attach the disk in the bag via the cables to your 
systemrescuecd machine. The paper towel inside the bag will prevent the disk 
from condensation from moisture getting in through the gap for the cables. Rerun 
the last ddrescue command. The logfile will direct ddrescue to only attempt to 
recover the missing sectors

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) austintek (dot) com - azimuthal equidistant
map generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!