Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual page 99

8.1.2 The File device.map
The file device.map maps GRUB and BIOS device names to Linux device names.
In a mixed system containing IDE and SCSI hard disks, GRUB must try to determine
the boot sequence by a special procedure, because GRUB may not have access to the
BIOS information on the boot sequence. GRUB saves the result of this analysis in the
file /boot/grub/device.map. For a system on which the boot sequence in the
BIOS is set to IDE before SCSI, the file device.map could appear as follows:
(fd0) /dev/fd0
(hd0) /dev/sda
(hd1) /dev/sdb
Because the order of IDE, SCSI and other hard disks depends on various factors and
Linux is not able to identify the mapping, the sequence in the file device.map can
be set manually. If you encounter problems when booting, check if the sequence in this
file corresponds to the sequence in the BIOS and use the GRUB prompt to modify it
temporarily, if necessary. After the Linux system has booted, the file device.map
can be edited permanently with the YaST boot loader module or an editor of your
choice.
NOTE: Maximum Number of Hard Disks
To address a hard disk, GRUB uses BIOS services. This is done via the software
interrupt Int13h. Since Int13h is limited to handling a maximum number of
eight disks, GRUB can only boot from the disks handled by Int13h, even if there
are more disks present (which is often the case on multipath systems). The
device.map file created during the installation will therefore only contain a
maximum number of the eight disks handled by Int13h.
After manually changing device.map, execute the following command to reinstall
GRUB. This command causes the file device.map to be reloaded and the commands
listed in grub.conf to be executed:
grub --batch < /etc/grub.conf
The Boot Loader GRUB 85