Installation guide

where the BIOS could not find a file after the 1024 cylinder head of the disk. LBA support al-

lows GRUB to boot operating systems from partitions beyond the 1024-cylinder limit, so long

as the system BIOS supports LBA mode. Most modern BIOS revisions support LBA mode.

• GRUB can read ext2 partitions. This functionality allows GRUB to access its configuration

file, /boot/grub/grub.conf, every time the system boots, eliminating the need for the user to

write a new version of the first stage boot loader to the MBR when configuration changes are

made. The only time a user needs to reinstall GRUB on the MBR is if the physical location of

the /boot/ partition is moved on the disk. For details on installing GRUB to the MBR, refer to

Section 3, “Installing GRUB”.

3. Installing GRUB

If GRUB was not installed during the installation process, it can be installed afterward. Once in-

stalled, it automatically becomes the default boot loader.

Before installing GRUB, make sure to use the latest GRUB package available or use the GRUB

package from the installation CD-ROMs. For instructions on installing packages, refer to the

chapter titled Package Management with RPM in the Red Hat Enterprise Linux Deployment

Guide.

Once the GRUB package is installed, open a root shell prompt and run the command /

sbin/grub-install <location>, where <location> is the location that the GRUB Stage 1 boot

loader should be installed. For example, the following command installs GRUB to the MBR of

the master IDE device on the primary IDE bus:

/sbin/grub-install /dev/hda

The next time the system boots, the GRUB graphical boot loader menu appears before the ker-

nel loads into memory.

Important

If GRUB is installed on a RAID 1 array, the system may become unbootable in the

event of disk failure. An unsupported workaround is provided online at the follow-

ing URL:

http://www.dur.ac.uk/a.d.stribblehill/mirrored_grub.html

4. GRUB Terminology

One of the most important things to understand before using GRUB is how the program refers

to devices, such as hard drives and partitions. This information is particularly important when

configuring GRUB to boot multiple operating systems.

4.1. Device Names

3. Installing GRUB