Repair partition after dd

[Andrea Neroni <bignero_86@yahoo.it>]

Hi all,

While preparing a bootable USB a wild dd command was executed on the wrong partition, namely on /dev/sda5 instead of the intended /dev/sdb.

The consequences are easy to imagine. However, as the start of the disk has not been touched (the command run on sda5) I still have some hope to be able to recover part of the data before wiping out the disk and reinstalling (the overwritten portion of the disk is very small).

Running fdisk on /dev/sda yields the following:

> fdisk -l /dev/sda

Disk /dev/sda: 596.17 GiB, 640135028736 bytes, 1250263728 sectors

Disk model: SAMSUNG HM641JI 

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disklabel type: dos

Disk identifier: 0x3d27ec68

Device     Boot   Start        End    Sectors   Size Id Type

/dev/sda1  *       2048    1050623    1048576   512M  b W95 FAT32

/dev/sda2       1052670 1250263039 1249210370 595.7G  5 Extended

/dev/sda5       1052672 1250263039 1249210368 595.7G 83 Linux

The partition table should be intact, sda5 is a partition inside the extended sda2. The partition should be Ext4.

Question: having those information, is it possible to repair the partition to a state where I can copy away as much data I can and how can I do it?

Thanks to everybody!

Andrea

PS: yes, I know, data should have been backed up. Lesson learned.