Just had a situation where I ran palimpsest and tried to carve another partition onto a 2TB disk which I had only put a single 500GB partition on. To cut a long story short I ended up losing the current partition on the disk which was also my /home. So not fun.

In the end I did the following:

ddrescued the entire 2TB onto a 3TB External USB Drive a process that was best described as glacial (Googling about it there was a lot of blame being thrown at the WD Caviar Green Drive that I have)

Next up I ran testdisk and it found the missing partition and recovered it. Thoroughly recommend testdisk. Easy to use and the wiki has a good screenshotted step by step.

Next I copied everything off the recovered partition onto the external USB and then repartitioned the drive, this time I did all the partitioning and formatting with fdisk and mkfs.ext4 -b 4096.

The 4096 was so that I could match the file system to the hard disk block size. I think.

# for posterities sake I'm storing my disk layout on the 
# internet so I can recover it the next time I make the 
# mistake of toasting my drive. 

fdisk -l /dev/sdb

Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000c571c

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048   976758839   488378396   83  Linux
/dev/sdb2       976758840  1953515631   488378396   83  Linux
/dev/sdb3      1953515632  2930272423   488378396   83  Linux
/dev/sdb4      2930272424  3907029167   488378372   83  Linux

It's weird that these drives report two different logical / physical sector sizes.

It's WD's attempt to provide XP compatible drives. I think.

For more information on data recovery options other than the DIY stuff above visit https://www.cloudwards.net/best-data-recovery-software/