Chapter 4. Boot Loaders

79

The following command installs GRUB to the MBR of the master IDE device on the primary IDE

bus, alos known as the C drive:

/sbin/grub install /dev/hda

The next time you boot the system, you should see the GRUB graphical boot loader menu before the

kernel loads.

4.4. 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.

4.4.1. Device Names

The first hard drive of a system is called

(hd0)

by GRUB. The first partition on that drive is called

(hd0,0)

, and the fifth partition on the second hard drive is called

(hd1,4)

. In general, the naming

convention for file systems when using GRUB breaks down in this way:

( type of device

bios device number , partition number )

+

,-+

,

+

,

The parentheses and comma are very important to the device naming conventions. The

type of 

+

device

refers to whether a hard disk (

hd

) or floppy disk (

fd

) is being specified.

,

The

bios device number

is the number of the device according to the system's BIOS, starting

+

,

with

0

. The primary IDE hard drive is numbered

0

, while the secondary IDE hard drive is numbered

1

.

The ordering is roughly equivalent to the way the Linux kernel arranges the devices by letters, where

the

a

in

hda

relates to

0

, the

b

in

hdb

relates to

1

, and so on.

Note

GRUB's numbering system for devices starts with 0, not 1. Failing to make this distinction is one of

the most common mistakes made by new GRUB users.

The

partition number

relates to the number of a specific partition on a disk device. Like the

+

,

bios device number

, the partition numbering starts at

0

. While most partitions are specified

+

,

by numbers, if a system uses BSD partitions, they are signified by letters, such as

a

or

c

.

GRUB uses the following rules when naming devices and partitions:

It does not matter if system hard drives are IDE or SCSI. All hard drives start with

hd

. Floppy disks

start with

fd

.

To specify an entire device without respect to its partitions, simply leave off the comma and the

partition number. This is important when telling GRUB to configure the MBR for a particular disk.

For example,

(hd0)

specifies the MBR on the first device and

(hd3)

specifies the MBR on the

fourth device.

If a system has multiple drive devices, it is very important to know the drive boot order set in the

BIOS. This is rather simple to do if a system has only IDE or SCSI drives, but if there is a mix of

devices, it can become confusing.