Retrieving the file-system from a lost Linux partition

When you lost a Linux partition on Storage device, there is a 80% chance that you can retrieve the file-system in it just by Re-creating the lost Partition. I have tried couple of times in the recent past and it worked successfully.

Here's the sequence of steps which I performed to retrieve the file-system "/us2001" on a lost partition from a SAN disk:

[root@server-tap04 mapper]# mount -t ext3 /dev/mapper/us2001np1 /us2001

mount: special device /dev/mapper/us2001np1 does not exist

[root@server-tap04 mapper]# fdisk -l /dev/mapper/us2001n

 Disk /dev/mapper/us2001n: 10.7 GB, 10737418240 bytes

64 heads, 32 sectors/track, 10240 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Disk /dev/mapper/us2001n doesn't contain a valid partition table

[root@server-tap04 mapper]#

[root@server-tap04 mapper]# multipath -l | grep -A5 us2001n

us2001n (350002ac009290783)

[size=10 GB][features="1 queue_if_no_path"][hwhandler="0"]

\_ round-robin 0 [active]

\_ 1:0:0:1 sdc 8:32 [active]

\_ 2:0:0:1 sdb 8:16 [active]

[root@server-tap04 mapper]# fdisk -l /dev/sdc

 Disk /dev/sdc: 10.7 GB, 10737418240 bytes

 64 heads, 32 sectors/track, 10240 cylinders

 Units = cylinders of 2048 * 512 = 1048576 bytes

 Disk /dev/sdc doesn't contain a valid partition table

[root@server-tap04 mapper]# fdisk /dev/sdc

Command (m for help): n

Command action

   e   extended

   p   primary partition (1-4)

p

Partition number (1-4): 1

First cylinder (1-10240, default 1):

Using default value 1

Last cylinder or +size or +sizeM or +sizeK (1-10240, default 10240):

Using default value 10240

Command (m for help): w

The partition table has been altered!

 Calling ioctl() to re-read partition table.

Syncing disks.

[root@server-tap04 mapper]# kpartx -a /dev/mapper/us2001n

[root@ server-tap04 mapper]# kpartx -l /dev/mapper/us2001n

us2001np1 : 0 20971488 /dev/mapper/us2001n 32

[root@rica-chi-tap04 mapper]# mount -t ext3 /dev/mapper/us2001np1 /us2001

[root@rica-chi-tap04 mapper]# df -h /us2001
Filesystem            Size  Used Avail Use% Mounted on

/dev/mapper/us2001np1

                      9.9G  5.8G  4.1G  59% /us2001

[root@rica-chi-tap04 mapper]# cd /us2001                <-- Partition recreated and mounted  

[root@rica-chi-tap04 us2001]# ls -l                           <-- All the files are retrieved

total 28

-rw-r--r--  1 root     root     0 Jan 18  2011 2

-rw-r--r--  1 root     root     0 Jan 18  2011 abc

drwxr-xr-x  5 appltest dba   4096 Aug 10  2010 BI_Disco10g

drwx------  2 root     root 16384 Aug  6  2010 lost+found

drwxr-xr-x  4 appltest dba   4096 Mar 11  2011 product

[root@server-tap04 us2001]# touch xyz
[root@server-tap04 us2001]#