Need to manually edit partition table

charrah · 08-24-2009, 09:36 AM

Ok well yesterday I installed the Windows 7 RC alongside my existing Ubuntu Jaunty installation and for some reason it removed the entry for the main ext4 partition from the table. I used testdisk and it found the ext4 partition, but it improperly discovered the NTFS partitions at the beginning of the hard drive and while my Ubuntu installation is safe and working now, the 2 NTFS partitions Windows had created have merged into one unmountable partition. I want to edit the partition table to properly show the NTFS partitions, but of course keep my Linux partitions. Thankfully I have a copy of the fdisk -l output before I ran testdisk, so I don't think there should be any guesswork.

Before testdisk:

Code:

Disk /dev/sda: 80.0 GB, 80000000000 bytes
255 heads, 63 sectors/track, 9726 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xe686f016

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      102400    7  HPFS/NTFS
Partition 1 does not end on cylinder boundary.
/dev/sda2              13        6444    51657728    7  HPFS/NTFS
/dev/sda3            6445        9726    26362665    5  Extended
/dev/sda5            9229        9726     4000185   82  Linux swap / Solaris

After testdisk:

Code:

Disk /dev/sda: 80.0 GB, 80000000000 bytes
255 heads, 63 sectors/track, 9726 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xe686f016

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        6444    51761398+   7  HPFS/NTFS
/dev/sda2            6445        9227    22354416    f  W95 Ext'd (LBA)
/dev/sda3            9229        9726     4000185   82  Linux swap / Solaris
/dev/sda5            6445        9227    22354384+  83  Linux

So my new partition table needs to have those two distinct NTFS partitions listed as in the first table, but keep my ext4 partition there. (the more I look at the second fdisk output, the more I worry testdisk left something to be desired actually; some of those start/end numbers don't seem quite right)

Valery Reznic · 08-25-2009, 11:13 AM

So, what's your question ?

charrah · 08-25-2009, 03:23 PM

My question was how I would edit the partition table by hand to get the kind of setup I described; however since I had already broken so many things in Linux and didn't care for Windows 7 particularly I cut my losses, backed up, and reinstalled.

Valery Reznic · 08-25-2009, 11:09 PM

Quote:

Originally Posted by charrah

My question was how I would edit the partition table by hand to get the kind of setup I described; however since I had already broken so many things in Linux and didn't care for Windows 7 particularly I cut my losses, backed up, and reinstalled.

For the next time your partition table will messed up

Using fdisk is quite simple:
Run it, and then you provided with menu.
You should delete all existing partitions, and then create new ones
(using start and end cylinder information you have) and set appropriative
type and boot flag.

Nothing you do in fdisk written back to disk unless you give 'w' command,
so there is always way back.

Another possibility before doing something dangerous ( == installing Windows) backup your partition table (or whole MBR) with dd command.
Then you'll be able tp restore it using same dd