I made a default installation of Fedora 16 on my testing machine the other day and Anaconda has installed GPT on the hard drive. Now, I want to fall back to MBR. Wildly used tool fdisk was showing a message Warning!! Unsupported GPT (GUID Partition Table) detected. Use GNU Parted. Frankly, I did not like it at all.
My first idea was to get rid of the first few sectors on the hard drive:
dd if=/dev/zero of=/dev/sda bs=512 count=1
Guess what, it did not work. After some time spend on the internet I found out GPT has a "backup" entry at the very end of the disc. I tried to copy zeroes over it, but it did not work too. The trick is quite easy, but it was more difficult to google this time:
parted /dev/sda mklabel msdos quit
Finally, the disc is back to traditional MBR. I think I don't like new things, sometimes.