Installation guide

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><bios-device-number>,<partition-number>)

The <type-of-device> specifies the type of device from which GRUB boots. The two most com-

mon options are hd for a hard disk or fd for a 3.5 diskette. A lesser used device type is also

available called nd for a network disk. Instructions on configuring GRUB to boot over the net-

work are available online at http://www.gnu.org/software/grub/manual/.

The <bios-device-number> is the BIOS device number. The primary IDE hard drive is numbered

0 and a secondary IDE hard drive is numbered 1. This syntax is roughly equivalent to that used

for devices by the kernel. For example, the a in hda for the kernel is analogous to the 0 in hd0 for

GRUB, the b in hdb is analogous to the 1 in hd1, and so on.

The <partition-number> specifies the number of a partition on a device. Like the

<bios-device-number>, most types of partitions are numbered starting at 0. However, BSD parti-

tions are specified using letters, with a corresponding to 0, b corresponding to 1, and so on.

Tip

The numbering system for devices under GRUB always begins with 0, not 1. Fail-

ing to make this distinction is one of the most common mistakes made by new

users.

To give an example, if a system has more than one hard drive, GRUB refers to the first hard

drive as (hd0) and the second as (hd1). Likewise, GRUB refers to the first partition on the first

drive as (hd0,0) and the third partition on the second hard drive as (hd1,2).

In general the following rules apply when naming devices and partitions under GRUB:

• It does not matter if system hard drives are IDE or SCSI, all hard drives begin with the letters

hd. The letters fd are used to specify 3.5 diskettes.

• To specify an entire device without respect to partitions, leave off the comma and the parti-

tion 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 how the drive boot order is

set in the BIOS. This is a simple task if a system has only IDE or SCSI drives, but if there is

a mix of devices, it becomes critical that the type of drive with the boot partition be accessed

first.

4.2. File Names and Blocklists

When typing commands to GRUB that reference a file, such as a menu list, it is necessary to

specify an absolute file path immediately after the device and partition numbers.

4.2. File Names and Blocklists