I have lost the /boot partition by trying to multi-boot with openSUSE, is there a quick way I can re-run just the boot-loader part of the install routine to restore this or do I need to go through the whole install process again?

The original install had a separate /boot partition which contained the boot loader, I then installed openSUSE using the same /boot partition which I hoped would allow multi-boot between the two of them. Unfortunately that didn't work.

Thanks,
Nick

Well I found that in theory I could do this by running the DVD setup and choosing the upgrade option. Unfortunately this falls over with the unhandled exception:

archictecture: x86_64
cmdline: /usr/bin/python /usr/bin/anaconda
executable: /usr/bin/anaconda
kernel: 2.6.32-220.el6.x86_64
package: cannot get package and component file for file /usr/bin/anaconda
release: cannot get release name
other involved packages:

anaconda 13.21.149 exception report
Traceback (most recent call first):
File "/usr/lib/anaconda/booty/x86.py", line 258, in writegrubconf
f = open(cf, "W+ ")
...
...
IOError: [Errno 2] No such file of directory: '/mnt/sysimage/boot/grub/grub.conf'

Sharing /boot between distros is a Bad Idea [TM] as you have discovered. You might be able to recover by copying /boot from a working CentOS system, but trying to reinstall or do an anaconda upgrade in an attempt to recover does not seem like a viable approach. Your best bet if you haven't got another system to use as a recovery source is a backup and fresh install.

If you want to multi-boot then about all you can safely share is swap, and possibly some data storage, and that only under certain conditions such as not having it on LVM. Doing an install to a totally separate location and writing the bootloader for one distro or the other to the boot record on the boot partition, rather than the MBR, then chainloading it from whatever owns the MBR is the right way to go. The MBR owner should usually be whichever distro has the later GRUB. For LILO or other bootloaders I cannot advise.

Ok thanks Phil, will try again using separate /boot for each distro.

If I have understood correctly I should be able to install:

CentOS - bootloader to CentOS /boot
openSUSE - bootloader to openSUSE /boot
Fedora - bootloader to MBR

Does that sound correct.

Yes. If you need help with chainloading try a forum search and see the Wiki articles on GRUB installation and troubleshooting.