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+Optional: Creating Backup of Existing GRUB Legacy Installation + + +

+Playing with bootloader always brings the danger of leaving your system in +unbootable state. Fortunately no data is lost in most cases and recovery is not +hard, but we recommend you to have a bootable CD, DVD or a USB flash disk with +Linux around (Gentoo +LiveDVD or System Rescue CD +will do) and to backup your current bootloader setup. If your current +bootloader is GRUB legacy, following code sample may help you backing it up. +

+ +

+# # copy grub modules and configuration
+# cp -a /boot/grub /path/to/backup/
+# # backup the MBR and GRUB stage 1.5
+# dd if=/dev/sda of=/path/to/backup/first-sectors count=63
+

+ + +Replace /dev/sda with device node of the disk you boot from (this is +usually and the whole disk like sda, not a partition like sda1) and +/path/to/backup with path to your favourite backup medium. + + +

+When something goes wrong, you can restore previous grub installation by +booting some Linux live media and issuing following commands. +

+ +

+# # move old grub files out of the way
+# mv /boot/grub /boot/grub.nonfunctional
+# # copy grub back to /boot
+# cp -a /path/to/backup/grub /boot/
+# # replace MBR and next 62 sectors of sda with backed up copy (DANGEROUS!)
+# dd if=/path/to/backup/first-sectors of=/dev/sda count=63
+

+ + +Replace /dev/sda with device node of the disk you boot from and +/path/to/backup with path to the place where you've stored your backup. + + + +Writing directly to disk sectors (even those that are outside of partitions +in typical setup) is risky operation and will make your data inaccessible +if you changed your parititon layout between backup and restore. Other slower +and safer option would be chrooting into your Gentoo installation and +re-installing bootloader - you can use Gentoo +Handbook for that task. + + + +