[Bug 798285] Re: Installer won't detect existing oS or partition table.

[Martijn Heemels]

Somehow, all my messing around (see previous comment) had broken my
Windows 7 installation so that even the recovery tools on the Windows 7
cd could no longer fix it. Thankfully this was a fresh install, so I
decided to do some more testing.

I eventually used Disk Utility from an Ubuntu live-cd to create a new
partition table, then reinstalled Windows 7 on 50% of the drive. The
Ubuntu installer then correctly detected the Windows installation and
was able to install on the empty remaining 50%. The grub menu was also
correctly configured to dual-boot.

I think the bug was caused by the remaining GUID Partition Table from OS
X Lion. It appears the Windows installer does not correctly create a new
table when you use it to delete all current partitions and create new
ones. Windows was able to install and boot fine, but Ubuntu's installer
got confused by the remaining GPT stuff. I don't know enough about this
to really know. Creating a new MS-DOS partition table apparently created
a fresh slate to work on.

This is probably a bit of an edge case, since it would involve three
OS's in a specific sequence, but it may be worth looking into because of
the potential for data loss. A clueless user would easily wipe his
entire disk, and even my careful (I thought) attempts to troubleshoot
ruined the Windows partition.

I guess the following steps would reproduce this bug:
1. Create GPT partition table with OS X.
2. Boot Windows 7 installer and select manual partitioning
3. Remove all partitions via Windows installer.
4. Create new partition taking about 50% of the drive. Windows automatically creates a small (100MB) recovery partition too.
5. Install Windows.
6. Boot from Ubuntu cd.
7. Bug: Ubuntu installer can't detect Windows installation, and offers to overwrite the whole disk. Manual partitioning also shows the entire disk to be empty. Disk Utility or Gparted do show some partitions, but incorrectly, and any actions on the disk fail, potentially damaging the actual partitions beyond easy repair.

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https://bugs.launchpad.net/bugs/798285

Title:
  Installer won't detect existing oS or partition table.

Status in “ubiquity” package in Ubuntu:
  Confirmed

Bug description:
  I was trying to install a newer version of Ubuntu, 10.04/10.10. When I
  use live CD, it won't detect any existing OS or partitions. Same with
  Alternative installer: It won't see any partitions, just my hard
  drive. There have been many questions about this but none of them
  seemed to help.

  I wanted to have a new version of Ubuntu but preferably without having
  to re-install windows as well. I really don't know where the partition
  table went. The installers just don;t see anything. Both operating
  systems work fine, GRUB is always working correctly.

  The problem is described in more detail in question #159921. I hope
  this helps.

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