Ubuntu – Fixing corrupt backup GPT table

Chances are your disk originally contained a GUID Partition Table (GPT), but you created a new Master Boot Record (MBR) partition table over that with a tool that doesn't understand GPT. Because GPT takes up more space than MBR, this means that there's leftover GPT data, and parted is becoming confused because of that.

If this analysis is correct, then the easiest solution is to run FixParts on the disk. FixParts will offer to remove the leftover GPT data, and thereafter you should be able to use the disk normally. (You don't need to do anything else in FixParts; just tell it to remove the GPT data when it asks you about this and then exit.)

There is a caveat, though: It's also possible that you had a GPT disk but that something accidentally wrote an MBR partition table to the disk. In this case, you probably want to recover the GPT, not wipe it out! If this is the case, the solution is to run gdisk on the disk. It will detect the problem and ask if you want to use the GPT or MBR data. Tell it to use the GPT data, check that it's correct by typing p and comparing the output to whatever you believe to be correct, and then type w to save the changes.

Both FixParts (fixparts) and gdisk are part of the gdisk package in Ubuntu. It's usually not installed by default, so you may have to install it by typing sudo apt-get install gdisk.

The overlapping data suggests that you did not have a GPT disk to begin with, but in fact had an MBR disk and were booting in BIOS mode. (One of gdisk's features is that it automatically converts from MBR to GPT when you launch it on an MBR disk.) If I'm right, you can probably restore the MBR as follows:

1. Launch gdisk, as in your example.
2. Load the (converted-to) GPT backup data, as in your example.
3. Type r to enter the recovery & transformation menu.
4. Type g to convert the GPT data to MBR form (in memory). You'll see a new MBR command prompt.
5. Type p to view your converted-to-MBR partition table.
6. Review the output to be sure that all the partitions are present -- none should be listed as omitted in the Status column. You may want to review the FixParts documentation, as FixParts uses this same menu, and the documentation describes the options in more detail.
7. Once you're satisfied that all your partitions are present and set as they should be, type w to save your changes and exit.

OTOH, if you're positive that the disk was in GPT form and that the computer was booting Windows in EFI mode, then your partition table was simply damaged to begin with. In this case, you may need to delete that final partition and re-create it a little bit smaller to make it fit; gdisk won't let you save a damaged partition table.