So it’s clear we would like to switch the default bootloader to grub2…lets try “install and test grub2”.
If you are running Jaunty Jackalope or later, grub2 can be installed in parallel with, and as a chainloaded sub-bootloader of, your existing grub installation. This allows you to boot actually with grub and then select grub2 from the menu. Then you can confirm grub2 works correctly before electing to switch to it formally.
Note: If you do this from Jaunty YOUR MACHINE WILL NOT BOOT. Read the instructions about changing “root” to “uuid” below.
Though it is unlikely you will have any issues it is always recommend taking precautions before attempting a bootloader update. It is recommended that you have an up to date backup of your system before attempting this. It is also recommended that you have a bootable CD or a bootable USB disk available should you be unable to boot following the installation.
How to Install grub2
$ sudo apt-get install grub-pc
At the first prompt, select OK. Next, at the “Chainload from menu.lst” prompt answer “Yes”. And at the “Linux command line:” prompt just press the Enter key.
This will install grub2 and modify the existing grub boot loader menu allow one to chain load grub2 to allow one to test to see if grub2 works on your machine. At this stage, the original grub is still the main boot loader and keeps the original boot menu items.
Note: In Jaunty (but not Karmic), there was a bug in the grub2 installer (LP#376879) where it modifies the existing grub configuration incorrectly. If you experience this problem, at the “Chainload into Grub 2” menu item, press ‘e’ to edit the configuration. Press ‘e’ a second time to edit the top boot line and change:
and press the Enter key after editing this line. Then press ‘b’ to chainload and boot grub2.
Note: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx is your partition UUID number.
If one can boot from grub2 successfully, one can then install grub2 onto the system as the main boot loader using the command:
$ sudo upgrade-from-grub-legacy
For alternative tests and more see here