UPDATE: this approach is deprecated and does not work on SINGLE GPT partitions bigger
than 2.2 TB.
Use my updated guide to install Centos5.5 instead:
I completely wasted a lot of time trying to get Centos5 running on some HP proliant server system.
After reading endless tutorials and tips I gave up...none of them worked...its impossible (at the moment) to install Centos5.x on a GPT system like mine (as others also stated).
In the end after partitoning or doing installer tricks such as erasing MBR with dd to pass the GPT check etc. I always stuck at the point that the installer does not recognize my smart array HP raid5.
So after all this approaches do not work I found the following solution:
-Install centos 4.8 which works perfectly well with GPT layout.
But before you can do this you have to upgrade your firmware to the latest edition because otherwise centos anaconda installer will fail with some GPT/MSDOS recognition problems.
-So I updated my clusters which come with a firmware from march2010 to the latest 9.03.
-Use a boot partition and install grub in this partition.
-After installation of some base packages immediately put in the latest linux rescue cd (http://www.sysresccd.org) and install new grub with GPT support because the one shipped with 4.8 does not support GPT partitions and grub will not load (red screen of death) the system.
Immediately after installation has finished installing insert linux rescue cd, reboot, I have 64 so chose 64bit version from the rescue cd menue and install a patched grub with gpt support:
mv /boot /boot_livecd
mount /dev/sda1 /boot (my boot partition is on sda1 to find out yours: parted /dev/sda print)
#make a backup of grub...for worst case scenario..
cp -r /boot/grub /boot/grub_original
edit /boot/grub/devices.map and replace entry "cc0011/c0d0" with "sda1"
grub will work and load the OS
Reboot and update your centos installation from 4 to 5 using a good other tutorial which can be found plenty of on the net.