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I have an Acer laptop with a 500 GB drive. It came with Windows 7 installed, and I installed Ubuntu 12.04 in a dual boot configuration. As far as I remember I installed everything accepting defaults all the way, but it was done over a year ago.

When copying a file from the Linux partition to the Windows partition it crashed. Of course this happened just after a lot of important work was done and before one of my (far to infrequent) backups was done. I do not have a "rescue disk" or backup of the partition table.

I Booted a 12.04.4 live CD, the disk utility shows that the Linux partition has disappeared. Everything else is there including the Linux swap partition, but the Linux partition is not listed, and its spot in the extended partition is shown as free space.

I am assuming only the partition table was damaged and the Linux partition is still there. The problem is determining exactly where the Linux partition starts, to recreate the partition table entry. My understanding is that it must be at least 63 blocks after the start of the extended partition, but can be more.

1) What's the best way to determine where the Linux partition starts?

2) Can I just copy the partition table with sfdisk, edit it and rewrite it, reboot, then mount the volume, or is there more that needs to be done?

user247447
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2 Answers2

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Two points:

  • Before you do anything else, and if the data has any value to you, make a clone of the hard-drive to a 2nd hard-drive (!)
  • Use testdisk on the copy to attempt to recover the partition table

See:

Community
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landroni
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gparted has a recovery option in the device menu (I myself have not used it). You can also use testdisk which is a tried and true piece of software. As landroni said, you should first make a bitwise copy of you drive, if you have an external drive at your disposal.

Back in the day when I still had a dual boot machine, I had a frightful experience like yours and then decided to use a dedicated NTFS partition to keep the files shared between the two systems (and so won't write from Linux partition to Windows one directly or vise versa.)

Reza
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    If you don't have an external drive at your disposal, buy one. Unfortunately speaking from experience.. – landroni Feb 12 '14 at 13:44