Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION, Руководство по установке

Страница: 114 / 388

Chapter 9. The GRUB Boot Loader
96
available called
nd
for a network disk. Instructions on configuring GRUB to boot over the network 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 partitions are
specified using letters, with
a
corresponding to
0
,
b
corresponding to
1
, and so on.
Note
The numbering system for devices under GRUB always begins with
0
, not
1
. Failing 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 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 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.
9.4.2. 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.
The following illustrates the structure of such a command:
( <device-type><device-number> , <partition-number> ) </path/to/file>
In this example, replace
<device-type>
with
hd
,
fd
, or
nd
. Replace
<device-number>
with the
integer for the device. Replace
</path/to/file>
with an absolute path relative to the top-level of
the device.
It is also possible to specify files to GRUB that do not actually appear in the file system, such as a
chain loader that appears in the first few blocks of a partition. To load such files, provide a
blocklist
that specifies block by block where the file is located in the partition. Since a file is often comprised
of several different sets of blocks, blocklists use a special syntax. Each block containing the file is