Recovering partition table using TestDisk and sfdisk

julkwiec · 07-16-2010, 06:02 AM

Hi. Something bad happened to my partition table, so right now I'm working from a Live CD. My partition table is completely screwed, although the data on the lost partitions hasn't been overwritten. I've been messing around with TestDisk for about an hour, but I still didn't figure out how to fix my problem.
Before the crash, I had 5 partitions:
NTFS - 30GB
NTFS - 8GB
ext4 - 20GB
and here comes the extended partition:
linux swap - 8 GB
NTFS - 400GB

TestDisk can see all those five partitions. I can mark swap as Logical, but I can't do so with the 400GB NTFS partition - there is just no selection. Turning on "expert mode" didn't help. I have read about using sfdisk to fix partition table, but I don't think I'm able to do it by myself. I would really appreciate your help

Here's how it looks in TestDisk:

Code:

Disk /dev/sda - 500 GB / 465 GiB - CHS 60802 255 63
     Partition               Start        End    Size in sectors
D HPFS - NTFS              0   1  1  3915 254 63   62910477
D HPFS - NTFS           3916   0  1  4959 254 63   16771860 [Windows XP]
D Linux                 4960   0  1  7539 254 63   41447700
L Linux Swap            7540   1  1  8583 254 63   16771797
D HPFS - NTFS           8584   0  1 60800 254 63  838866105 [Reszta]

and, here is my slightly modified sfdisk table dump:

Code:

# partition table of /dev/sda
unit: sectors

/dev/sda1 : start=         63, size= 62910477,  Id= 7
/dev/sda2 : start=   62910540, size= 16771860,  Id= 7
/dev/sda3 : start=   79682400, size= 41447700,  Id=83
/dev/sda4 : start=          , size=         ,  Id= 5   //extended partition
/dev/sda5 : start= 	     , size= 16771797, Id=82	//8gb swap
/dev/sda6 : start=           , size= 838866105, Id= 7   //400gb ntfs

I've filled sizes according to TestDisk's findings. First 3 partitions were OK, the problem
lies in the extended partition holding 2 logical ones.
By the way, TestDisk is able to enter the 400gb partition and see the files.

syg00 · 07-17-2010, 12:07 AM

If testdisk can't work it out, I'm betting you (us) won't either.
It won't let you mark it as a logical, because the allocation doesn't look like a logical - it doesn't have a room for the linked list to the next logical (effectively a sector zero).
Personally I wouldn't be rooting around with sfdisk unless I knew I had a decent backup to fall back on.

malekmustaq · 07-17-2010, 03:58 AM

Quote:

Hi. Something bad happened to my partition table, so right now I'm working from a Live CD. My partition table is completely screwed, although the data on the lost partitions hasn't been overwritten. I've been messing around with TestDisk for about an hour, but I still didn't figure out how to fix my problem.

Try using GParted, you might be able to control every partition there.

Quote:

TestDisk can see all those five partitions. I can mark swap as Logical, but I can't do so with the 400GB NTFS partition - there is just no selection. Turning on "expert mode" didn't help. I have read about using sfdisk to fix partition table, but I don't think I'm able to do it by myself. I would really appreciate your help

Try use "cfdisk" or "fdisk" commands in the terminal. You have better control there. Just be careful.

If you have important data on that NTFS partition you should back them up first before using those powerful commands.

Goodluck.