dual booting centos5.5 and fedora

Question

I already have centos5.5 on my system whose hard disk is ~500GB. I have tried to dual boot with fedora 16. while installing fedora 16 I have created a ~250GB and ~4GB partitions for "/" and swap. The installation has gone pretty smoothly until a error at the end said that installing bootloader has been unsuccessful. The grub at boot time only shows centos entries .Now when I boot into centos and run the lvm->lvscan .. it shows 4 partitions (2 swap spaces and two "/" partitions for centos and fedora 16). How can boot into fedora.

Answer 1

Since there is a bootable grub in your system, one way to boot Fedora would be to find its grub.cfg (probably /boot/grub/grub.conf when CentOS is running) and add an entry for Fedora.

While this is one possibility, leading to CentOS' grub handling everything, it might not be too comfortable, since changes to your Fedora installation that need to change Grub's config won't be able to do this, as Fedora's Grub is not in charge at all. A more comfortable option hence might be to chainload Fedora's Grub from CentOS' Grub (some related information here). This means you need to

1. properly boot into Fedora (maybe possible by using Ctrl+E on CentOS' entry and changing the values; probably possible by using Fedora's install medium again)
2. re-install its Grub at the beginning of its partition, i.e. (EXAMPLE only) /dev/sda4 instead of /dev/sda (where CentOS' Grub resides)

(I'm aware that this is not a step-by-step guide but a pointer into the rough direction; I cannot fill out the details as I do not know CentOS or Fedora's Grub handling. The proper way to add the chainloading directing probably involves some file in /etc/grub.d/ or some analogue, just editing grub.conf will be reverted on updates.)

Edit see also this question and its answers. If CentOS provides an os-prober package, there might be quicker and more comfortable solutions.