Thursday, 12 October 2006

Active OEM/EISA Partitions confuse upgrading Windows

I've been trialling Vista on a new Dell workstation.

This machine came configured with XP Home and an "OEM Recovery" partition.

I installed Vista onto the main partition by booting from a DVD.

What I didn't realise was that it appears the machine came configured with the OEM partition as the 'active' partition.

This didn't cause a problem until I then when to upgrade the build of Vista to a newer version.

The upgrade then complained that it didn’t have enough room for the temporary files to install Windows – even though my C: had 200 Gig free!

Turns out it was probably looking at the OEM partition, which was full.

How did I resolve this? After some clues about the cause of the problem from Darrell Gorter in the Microsoft Newsgroups, I did the following:

  1. First of all, I used diskpart.exe – a command-line tool to change the active partition to C: (it’ also in XP)
  2. This isn’t the whole solution, as now if you try and reboot the machine, you’ll get a "BOOTMGR is missing" error.
  3. So you boot off the OS media (Vista DVD in this case).
  4. Set the locale/keyboard settings and then choose 'Repair your computer'.
  5. It scans your disks for installs of Windows, then click 'Next'
  6. Then click on 'Startup Repair' - this figures out that BOOTMGR is missing and puts it in the right spot.
  7. The boot manager should now be fixed and you can reboot successfully.

If I'd originally booted XP Home, I suspect this problem would have been avoided. It appears that these machines modify the active partition when they boot the installed OS. As I'd just booted clean off of the DVD, this change never took place. I imagine this problem could affect any OS that tried to install on a similarly supplied workstation.

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