[CentOS] Need a Centos 6 USB hard drive recovery procedure

Sat Jun 1 04:18:38 UTC 2013
Rock <Rocksockdoc at gmail.com>

On Sat, 11 May 2013 22:28:53 +0200, Louis Lagendijk wrote:

> here is a quick list of what to do:
Thanks. I needed this step-by-step procedure; and I'll report back.
I bought a new 2TB disk, named "My Passport".
I will test the procedure with a spare 500GB disk, named "Signature Mini".

> 1) connect your spare disk (USB) (not the bad disk!!!!!) and as root
> check what device id it got (tail /var/log/messages) look for detected
> partitions there or do 
> fdisk -l /dev/sdx where the sdx is what you found from /var/log/messages

0. $ sudo tail -f /var/log/messages
1. I plugged in the 2TB new disk.
==> May 31 20:52:37 ntfs-3g[4213]: Mounted /dev/sdb1 (Read-Write, label "My Passport", NTFS 3.1)
2. $ sudo fdisk -l /dev/sdb
==> Disk /dev/sdb: 2000.4 GB, 2000365289472 bytes
==> /dev/sdb1 1 243198 1953480704 7 HPFS/NTFS

> 2) As root Mount the disk:
> mount /devsdxy /mnt 
> (where y is the partion number you want to mount)

3. $ sudo mount /dev/sdb1 /mnt
==> Mount is denied because the NTFS volume is already exclusively opened.
==> The volume may be already mounted, or another software may use it which
==> could be identified for example by the help of the 'fuser' command.

> if mounted goto 3
> This may fail if it is ntfs
> 2B) If it fails format the disk as ext4:
> mkfs /dev/sdxy
> and then mount it as under 2

Should I now format the 2TB disk using this command?
 $ sudo mkfs /dev/sdb1
And then mount it as:
 $ sudo mount /dev/sdb1 /mnt

> 3) I assume here that your bad disk is already connected (as sdz check
> first what the real name is)

At this point, I connect the 500GB test disk and this shows up
in the tail of /var/log/messages:
May 31 21:02:39 ntfs-3g[4787]: Mounted /dev/sdc1 (Read-Write, label "SignatureMini", NTFS 3.1)

> dd if=/dev/sdz of=/mnt/image.dd bs=1M
> This will copy the contents of your bad disk to image.dd

Is this the correct command given the test information above:
  $ sudo dd if=/dev/sdc of=/mnt/image.dd bs=1M
> 4) just to be sure, make the image read-only
> chmod uog=r /mnt/image.dd

I presume I do this after the previous dd command finishes.
  $ sudo chmod uog=r /mnt/image.dd
> 5) install testdisk from the epel repo
> yum install testdisk

  $ sudo yum --enablerepo epel install testdisk -y
  ==> Installed: testdisk.x86_64 0:6.12-2.el6                                                                                                                        
  ==> Dependency Installed: libewf.x86_64 0:20100226-1.el6 
  Note: This apparently installs /usr/bin/photorec  

> 6) now run photorec from a directory where you have sufficient space,
> ifg your usb disk is big enough do it there (hint create a sub-directory
> mdkdir /mnt/recover
> cd /mnet/recover

  You probably mean "mkdir", so is this what I run:
  $ sudo mkdir /mnt/recover
  $ cd /mnt/recover

> but any dorectory would do
> photorec /mnt/image.dd

  $ sudo photorec /mnt/image.dd

Q: Is this the recommended procedure as written after your comments?