Vvc: /* Install bootloader on second disk */

2009-07-22T15:39:46Z

Install bootloader on second disk

New page

=== Partition new disk ===
<pre>
[root@centos ~]# fdisk -l /dev/hda

Disk /dev/hda: 20.0 GB, 20020396032 bytes
255 heads, 63 sectors/track, 2434 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 13 104391 83 Linux
/dev/hda2 14 2434 19446682+ 8e Linux LVM
[root@centos ~]# fdisk -l /dev/hdb

Disk /dev/hdb: 40.0 GB, 40000000000 bytes
255 heads, 63 sectors/track, 4863 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

[root@centos ~]# cat /etc/fstab
/dev/vg0/root / ext3 noatime 1 1
/dev/vg0/tmp /tmp ext2 noatime 1 2
/dev/vg0/home /home ext3 noatime 1 2
/dev/vg0/var /var ext3 noatime 1 2
/dev/vg0/usr /usr ext3 noatime 1 2
LABEL=/boot /boot ext2 noatime 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/vg0/swap swap swap defaults 0 0

[root@centos ~]# fdisk /dev/hdb

The number of cylinders for this disk is set to 4863.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-4863, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-4863, default 4863): 13

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): FD
Changed system type of partition 1 to fd (Linux raid autodetect)

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (14-4863, default 14):
Using default value 14
Last cylinder or +size or +sizeM or +sizeK (14-4863, default 4863): +512M

Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 82
Changed system type of partition 2 to 82 (Linux swap / Solaris)

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (77-4863, default 77):
Using default value 77
Last cylinder or +size or +sizeM or +sizeK (77-4863, default 4863): 2434

Command (m for help): t
Partition number (1-4): 3
Hex code (type L to list codes): FD
Changed system type of partition 3 to fd (Linux raid autodetect)

Command (m for help): p

Disk /dev/hdb: 40.0 GB, 40000000000 bytes
255 heads, 63 sectors/track, 4863 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hdb1 1 13 104391 fd Linux raid autodetect
/dev/hdb2 14 76 506047+ 82 Linux swap / Solaris
/dev/hdb3 77 2434 18940635 fd Linux raid autodetect

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

</pre>

The new disk was larger, partition sizes were calculated based on old disk size.

=== Switch to new swap partition ===
:Note: You have to make a decision what is more important to you. If you want your system to continue to run in case of a hard disk failure, you need to go with 'swap on raid ' approach: don't create separate swap partitions, but instead create a swap logical volume in the new volume group. If performance is more important, then you split your swap between two disks and create separate swap partitions on each disk, as I did in this document.

<pre>
[root@centos ~]# mkswap -L swapb /dev/hdb2
Setting up swapspace version 1, size = 518184 kB
LABEL=swapb, no uuid

[root@centos ~]# swapon /dev/hdb2
[root@centos ~]# swapoff /dev/vg0/swap

</pre>

=== Install required packages ===
yum -y install mdadm dump

=== Create degraded RAID arrays ===
<pre>
[root@centos ~]# mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hdb1 missing
mdadm: array /dev/md0 started.
[root@centos ~]# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/hdb3 missing
mdadm: array /dev/md1 started.
[root@centos ~]# mdadm --examine --scan > /etc/mdadm.conf
</pre>

=== Create new volume group ===
<pre>
[root@centos ~]# pvcreate /dev/md1
Physical volume "/dev/md1" successfully created

[root@centos ~]# vgcreate -s 32M vg1 /dev/md1
Volume group "vg1" successfully created

[root@centos ~]# lvcreate --size 512M --name root vg1
Logical volume "root" created
[root@centos ~]# lvcreate --size 4G --name usr vg1
Logical volume "usr" created
[root@centos ~]# lvcreate --size 1G --name var vg1
Logical volume "var" created
[root@centos ~]# lvcreate --size 1G --name home vg1
Logical volume "home" created
[root@centos ~]# lvcreate --size 256M --name tmp vg1
Logical volume "tmp" created

</pre>

=== Format new filesystems ===
mkfs -j /dev/vg1/root
mkfs -j /dev/vg1/usr
mkfs -j /dev/vg1/var
mkfs -j /dev/vg1/home
mkfs /dev/vg1/tmp
mkfs /dev/md0

=== Shutdown all services ===
Keep sshd running, stop the rest

service crond stop
service syslog stop
...

=== Mount/transfer root volume ===
<pre>
mount -t ext3 /dev/vg1/root /mnt/
cd /mnt/
dump -0 -f - /dev/vg0/root | restore -r -f -
rm restoresymtable
</pre>

=== Mount/transfer remaining volumes ===
<pre>
mount -t ext3 /dev/vg1/usr /mnt/usr/
mount -t ext3 /dev/vg1/var /mnt/var/
mount -t ext3 /dev/vg1/home /mnt/home/
mount -t ext2 /dev/vg1/tmp /mnt/tmp/
chmod 1777 /mnt/tmp
mount -t ext2 /dev/md0 /mnt/boot/

cd /mnt/usr
dump -0 -f - /dev/vg0/usr | restore -r -f -
rm restoresymtable

cd /mnt/var
dump -0 -f - /dev/vg0/var | restore -r -f -
rm restoresymtable

cd /mnt/home
dump -0 -f - /dev/vg0/home | restore -r -f -
rm restoresymtable

cd /mnt/boot
dump -0 -f - /dev/hda1 | restore -r -f -
rm restoresymtable

</pre>

No need to dump/restore /tmp

=== chroot to new system ===
<pre>
mkdir /mnt/dev/pts
mount -t devpts devpts /mnt/dev/pts
mount -t sysfs sysfs /mnt/sys
mount -t proc proc /mnt/proc
mkdir /mnt/dev/shm
mount -t tmpfs tmpfs /mnt/dev/shm

chroot /mnt
start_udev
</pre>

=== adjust /etc/fstab ===
<pre>
[root@centos /]# cat /etc/fstab
/dev/vg1/root / ext3 noatime 1 1
/dev/vg1/tmp /tmp ext2 noatime 1 2
/dev/vg1/home /home ext3 noatime 1 2
/dev/vg1/var /var ext3 noatime 1 2
/dev/vg1/usr /usr ext3 noatime 1 2
/dev/md0 /boot ext2 noatime 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=swapb swap swap pri=1 0 0
</pre>

=== adjust /etc/grub.conf ===
<pre>
default=1
timeout=5
#splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-128.2.1.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg0/root
initrd /initrd-2.6.18-128.2.1.el5.img
title CentOS (2.6.18-128.2.1.el5)
root (hd1,0)
kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg1/root
initrd /initrd-2.6.18-128.2.1.el5.img
</pre>

=== adjust /etc/mdadm.conf ===
<pre>
DEVICE partitions
MAILADDR root
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=8ca072a8:085c91c0:52eada7c:6cc0931c
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=898f5b3c:670dcb6c:d422cdf5:eddafb24
</pre>

=== recreate initrd image ===
<pre>
cd /boot
mkinitrd -f initrd-2.6.18-128.2.1.el5.img -v 2.6.18-128.2.1.el5
</pre>

=== copy new grub.conf to old disk ===
exit # from chroot
cp /mnt/etc/grub.conf /etc/grub.conf

=== Update bootloader configuration ===
grub-install --recheck /dev/hda

=== reboot to new system on the raid ===
reboot

=== verify new installation ===
Make sure system is operational and everything is in order.
Up to this step all changes made were non-destructive and you could boot your old system from the grub menu.

=== Delete old volume group ===
This step is not really necessary, you could have reformatted the first disk, but this OS-friendly approach.
lvremove /dev/vg0/root
lvremove /dev/vg0/usr
lvremove /dev/vg0/var
lvremove /dev/vg0/tmp
lvremove /dev/vg0/swap
vgremove vg0
pvremove /dev/hda2

=== delete and create new partitions on the old disk ===
You the same commands as before
<pre>
[root@centos ~]# fdisk -l /dev/hda

Disk /dev/hda: 20.0 GB, 20020396032 bytes
255 heads, 63 sectors/track, 2434 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 1 13 104391 fd Linux raid autodetect
/dev/hda2 14 76 506047+ 82 Linux swap / Solaris
/dev/hda3 77 2434 18940635 fd Linux raid autodetect

</pre>

=== Add additional swap ===
<pre>
mkswap -L swapa /dev/hda2
</pre>

Add entry to /etc/fstab
LABEL=swapa swap swap pri=1 0 0

=== Add partitions to raid ===

mdadm --add /dev/md0 /dev/hda1
mdadm --add /dev/md1 /dev/hda3

wait until RAID fully synchronized:

<pre>
# watch cat /proc/mdstat

Every 2.0s: cat /proc/mdstat Wed Jul 22 18:21:38 2009

Personalities : [raid1]
md0 : active raid1 hda1[1] hdb1[0]
104320 blocks [2/2] [UU]

md1 : active raid1 hda3[2] hdb3[0]
18940544 blocks [2/1] [U_]
[=>...................] recovery = 7.3% (1398400/18940544) finish=11.3min speed=25826K/sec

unused devices: <none>

</pre>

===Adjust grub.conf ===
<pre>
default=0
timeout=5
hiddenmenu
title CentOS (2.6.18-128.2.1.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg1/root
initrd /initrd-2.6.18-128.2.1.el5.img
</pre>

=== Install bootloader on second disk ===
<pre>
# grub
grub> device (hd0) /dev/hdb
grub> root (hd0,0)
grub> setup (hd0)
grub> quit
</pre>

=== Final reboot ===
shutdown -r now

'''Enjoy'''

Convert to RAID - Revision history

Vvc: /* Install bootloader on second disk */