Linux GRUB and grub.conf troubleshooting - part1
Posted: Mon Jan 04, 2010 5:37 pmTroubleshooting GRUB requires knowing how grub works. Looking at a sample grub.conf file, we can see the commands that grub will accept at command line prompt.
One thing to know about grub is that it's configuration file (grub.conf) reside in the /boot directory. In some cases /boot is a directory on the root filesystem, or a filesystem of it's own. From grub's point of view, there is a difference.
If /boot is a directory on the root filesystem (like above), then all paths in grub.conf will be relative to /.
If /boot is a standalone filesystem, then all paths will be relative to /boot (instead of /boot/vmlinuz-2.6.9-42.ELsmp, it will be /vmlinuz-2.6.9-42.ELsmp).
For each stanza, there is the root command which defines where is the /boot directory for that specific Linux OS(disk & partition). After that, the kernel and initrd define where are the kernel image and the initial ram disk + other parameters, relative paths from /boot directory/filesystem.
- Code: Select all
node1# cat /boot/grub/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You do not have a /boot partition. This means that
# all kernel and initrd paths are relative to /, eg.
# root (hd0,0)
# kernel /boot/vmlinuz-version ro root=/dev/sda1
# initrd /boot/initrd-version.img
#boot=/dev/sda
default=1
timeout=5
serial --unit=0 --speed=9600
terminal --timeout=5 serial console
title Memtest86+ (1.26)
root (hd0,0)
kernel /boot/memtest86+-1.26 ro root=LABEL=/ idle=poll console=ttyS1,115200
title Red Hat Enterprise Linux AS (2.6.9-42.ELsmp)
root (hd0,0)
kernel /boot/vmlinuz-2.6.9-42.ELsmp ro root=LABEL=/ console=tty0 console=ttyS0,9600n8
initrd /boot/initrd-2.6.9-42.ELsmp.img
One thing to know about grub is that it's configuration file (grub.conf) reside in the /boot directory. In some cases /boot is a directory on the root filesystem, or a filesystem of it's own. From grub's point of view, there is a difference.
If /boot is a directory on the root filesystem (like above), then all paths in grub.conf will be relative to /.
If /boot is a standalone filesystem, then all paths will be relative to /boot (instead of /boot/vmlinuz-2.6.9-42.ELsmp, it will be /vmlinuz-2.6.9-42.ELsmp).
For each stanza, there is the root command which defines where is the /boot directory for that specific Linux OS(disk & partition). After that, the kernel and initrd define where are the kernel image and the initial ram disk + other parameters, relative paths from /boot directory/filesystem.