Installing Grub; Grub Terminology - Red Hat ENTERPRISE LINUX 3 Reference Manual

Chapter 2. Boot Loaders

2.3. 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 System Administration Guide.
Once the GRUB package is installed, open a root shell prompt and run the command
/sbin/grub-install
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

2.4. GRUB Terminology

One of the most important things to understand before using GRUB is how the program refers to de-
vices, such as hard drives and partitions. This information is particularly important when configuring
GRUB to boot multiple operating systems.
2.4.1. Device Names
When referring to a specific device with GRUB, do so using the following format (note that the
parentheses and comma are very important syntactically):
( type-of-device
The type-of-device specifies the type of device GRUB is booting from. The two most com-
mon options are for a hard disk or
hd
called for a network disk. Instructions on configuring GRUB to boot over the network are available
nd
online at http://www.gnu.org/manual/grub/.
The bios-device-number is the BIOS device number. The primary IDE hard drive is num-
bered and a secondary IDE hard drive is numbered
0
for devices by the kernel. For example, the
GRUB, the in
b hdb
The
partition-number
bios-device-number , most types of partitions are numbered starting at
partitions are specified using letters, with
, where
location
bios-device-number , partition-number )
for a 3.5 diskette. A lesser used device type is also available
fd
is analogous to the
1
specifies the number of a partition on a device. Like the
location
. This syntax is roughly equivalent to that used
1
in for the kernel is analogous to the
a hda
in , and so on.
hd1
corresponding to
a 0
is the location that the GRUB Stage
0
, corresponding to
b
13
in for
0 hd0
. However, BSD
, and so on.
1