Grub naming methods:
====
1) All hard disks are designated by hd or sd.
2) All partitions are designated with numbers stating with 0 and 1.
3) Extended partitions are counted from 4 whether or not the primary partitions are present.
4) The first number is related to disk and second number is related to partition in that disk.
Examples:
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(hd0)
===
It means first hard disk, usually is /dev/sda or /dev/hda.
====
(hd1)
===
It means second hard disk, usually it is /dev/sdb or /dev/hdb
===
(hd0,0)
===
It means first hard disk, first partition. That is /dev/sda1 or /dev/hda1
===
(hd0,1)
===
It means first hard disk, second partition. That is /dev/sda2 or /dev/hda2
===
(hd1,1)
===
Second hard disk, second partition. That is /dev/sdb2 or /dev/sdb2
===
If you open and view /etc/grub/grub.conf you can view the following details:
Note: the below case is where there is no separate partition for /boot.
====
1) Default=0: By default boot the first partition listed below:
2) timeout=10 : wait for 10 seconds before the user input.
3) splashimage : Show splash image while waiting for user input.
4) Name of the first possible boot partition.
5) Location of grub as per grub naming convention( actual partition /dev/sda6).
6) The 6th line consist of 5 parts as follows:
SEPARATE PARTITION FOR /boot
=====
Now, if we have a separate partition for /boot then the changes in /etc/grub/grub.conf, will be as follows:
1) The line beginning with root should indicate the partition for /boot and not partition of /.
2) The line starting with kernel must assume that the kernel (vmlinuz) is in /, not in /boot. However, the command root in that line must indicate the partition for /, not the partition for /boot
3) The line starting with initrd must assume that the initial ramdisk (initrd or initramfs) is in /, not in /boot.
Example:
====
The /boot partition is /dev/sda1, or hd(0,0). The / partition is /dev/sda2, or hd(0,1). The file /boot/grub/grub.conf must indicate the following:
===
====
1) All hard disks are designated by hd or sd.
2) All partitions are designated with numbers stating with 0 and 1.
3) Extended partitions are counted from 4 whether or not the primary partitions are present.
4) The first number is related to disk and second number is related to partition in that disk.
Examples:
=====
(hd0)
===
It means first hard disk, usually is /dev/sda or /dev/hda.
====
(hd1)
===
It means second hard disk, usually it is /dev/sdb or /dev/hdb
===
(hd0,0)
===
It means first hard disk, first partition. That is /dev/sda1 or /dev/hda1
===
(hd0,1)
===
It means first hard disk, second partition. That is /dev/sda2 or /dev/hda2
===
(hd1,1)
===
Second hard disk, second partition. That is /dev/sdb2 or /dev/sdb2
===
If you open and view /etc/grub/grub.conf you can view the following details:
Note: the below case is where there is no separate partition for /boot.
====
1 default=0 2 timeout=10 3 splashimage=(hd0,5)/boot/grub/splash.xpm.gz 4 title CentOS 5.6 i686 5 root (hd0,5) 6 kernel /boot/vmlinuz-2.6.18-238.19.1.el5.centos.plusPAE ro root=/dev/sda6 rhgb noquiet 7 initrd /boot/initrd-2.6.18-238.19.1.el5.centos.plusPAE.img 8 title Linux Mint 11 9 root (hd0,9) 10 kernel /boot/vmlinuz-2.6.32-26-generic-pae ro root=/dev/sda10 11 initrd /boot/initrd.img-2.6.32-26-generic-pae
======
All these entries has got some meaning. I will explain here what are those.
1) Default=0: By default boot the first partition listed below:
2) timeout=10 : wait for 10 seconds before the user input.
3) splashimage : Show splash image while waiting for user input.
4) Name of the first possible boot partition.
5) Location of grub as per grub naming convention( actual partition /dev/sda6).
6) The 6th line consist of 5 parts as follows:
/boot/vmlinuz-2.6.18-238.19.1.el5.centos.plusPAE ==> The location of kernel.
---
ro
---
Mount the partition as read only and run fsck if necessary.
---
root=/dev/sda6
---
Location of root partition. The can be also UUID(universally unique identifier)
rhgb
----
Use graphical boot
----
noquiet
----
Be more verbose
----7) Location of intird or initramfs.
SEPARATE PARTITION FOR /boot
=====
Now, if we have a separate partition for /boot then the changes in /etc/grub/grub.conf, will be as follows:
1) The line beginning with root should indicate the partition for /boot and not partition of /.
2) The line starting with kernel must assume that the kernel (vmlinuz) is in /, not in /boot. However, the command root in that line must indicate the partition for /, not the partition for /boot
3) The line starting with initrd must assume that the initial ramdisk (initrd or initramfs) is in /, not in /boot.
Example:
====
The /boot partition is /dev/sda1, or hd(0,0). The / partition is /dev/sda2, or hd(0,1). The file /boot/grub/grub.conf must indicate the following:
===
title CentOS 5.6 i686 root (hd0,0) kernel /vmlinuz-2.6.18-238.19.1.el5.centos.plusPAE ro root=/dev/sda2 initrd /initrd-2.6.18-238.19.1.el5.centos.plusPAE.img
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