Windows 7 screws with your partitions

As my Dell XPS laptop’s video card failed (I’m looking at you - ‘olde nVidia with yer heating and packaging problems) and I had a corrupt Linux installation, I was suddenly in the mood to give Windows 7 a spin (There were a few games I still could only play in Windows).

Windows 7 truly is nice - but I was in for a rude surprise when I got ready to install Karmic Koala. I have separate home and root partitions to keep up with my ever changing base installs. As a force of habit (which comes from the Redhat 6.0 days, where you could not boot if the primary partition was not in the first 8GB), I create primary partitions for all my mounts.

When Win7 started to be installed, I had 50 GB of unutilised space lying around in my HDD. What Win7 does is create two partitions  - one for the main install and another 100mb partition for recovery. Now partition table holds a maximum of 4 entries - which means if you want more than 4 partitions, you need to have an extended partition somewhere (with anything over 4 partitions under it).

What Win7 does is silently, knock out one of the linux partitions from the partition table and creates two partitions for itself. It was catastrophic, because it knocked out my home folder. Now, I was not able to access my home partition, even by booting a linux livecd and using gparted.

After a lot of googling, I found Testdisk - a truly excellent, open source partition recovery software that works on windows and linux.

All I had to do is mark my home partition and write the partition table - this causes everything else to get screwed up (including my Win 7 partitions), but I was OK with that.

The only way around is prevention - always install windows 7 on an extended partition if you have more than one OS on it. The next time around I installed Win7, I pre-created extended partitions using gparted and installed Win7 on the extended partitions - note that the Win7 installer does not give you any sort of partition manager (the way Linux does)


Windows 7 screws with your partitions


October 07, 2009

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