Red Hat Enterprise Linux Installation Guide 5.2 - linux.meuhobby.com

Installing GRUB
• GRUB supports Logical Block Addressing (LBA) mode. LBA places the addressing
conversion used to find files in the hard drive's firmware, and is used on many IDE and all
SCSI hard devices. Before LBA, boot loaders could encounter the 1024-cylinder BIOS
limitation, where the BIOS could not find a file after the 1024 cylinder head of the disk. LBA
support allows 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
installed, 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 , where 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
kernel 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
following URL:
http://www.dur.ac.uk/a.d.stribblehill/mirrored_grub.html
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