= Software Raid on CentOS

# Add harddisk

# Check the disk that you add

> fdisk -l

Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14        2610    20860402+  8e  Linux LVM

Disk /dev/sdb: 21.4 GB, 21474836480 bytes             ######!!!!  Added 20G Hard  !!!!!########
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table


> fdisk /dev/sdb
n
p
1
1   ###  for same with sda1 ###
13  ###  for same with sda1 ###

n
p
2  
14    ###  for same with sda2 ###
2610  ###  for same with sda2 ###

t     
1
fd    ### for RIAD ###

t
2
fd    ### for RIAD ###

a     ### for boot ###
1

p
w


## Make RAID ##
> mdadm --create /dev/md0 --auto=yes --level=raid1 --raid-devices=2 missing /dev/sdb1
> mdadm --create /dev/md1 --auto=yes --level=raid1 --raid-devices=2 missing /dev/sdb2

> echo 'DEVICE /dev/hd[a-z]* /dev/sd[a-z]*' > /etc/mdadm.conf
> mdadm --detail --scan >> /etc/mdadm.conf
> echo MAILADDR root >> /etc/mdadm.conf


## RAID for boot ##
> mkfs -t ext3 /dev/md0
> mount /dev/md0 /mnt/
> rsync -avz -e ssh --delete /boot/ /mnt/
> umount /mnt/
> umount /boot/
> mount /dev/md0 /boot/

> vi /etc/fstab
#LABEL=/boot             /boot                   ext3    defaults        1 2  ### comment out ###
/dev/md0             /boot                   ext3    defaults        1 2     ### ADD ###



## RAID FOR Volume ##


> pvcreate /dev/md1
> vgextend VolGroup00 /dev/md1
> pvmove /dev/sda2 /dev/md1
> vgreduce VolGroup00 /dev/sda2


## Reboot
> mkinitrd -f /boot/initrd-`uname -r`.img `uname -r`

##
when linux boot 
type e key

grub edit> root (hd0,0)
����change hd0 to hd1 ����
grub edit> root (hd1,0) 

#boot
b




> pvremove /dev/sda2
> fdisk -l /dev/sdb

> fdisk /dev/sda
p
d
1
d
p
n
p
1
1
13
p
2
14
2610
t
1
fd
t
2
fd
a
1
p
w



# ADD sda to md0
> mdadm /dev/md0 --add /dev/sda1
> mdadm /dev/md1 --add /dev/sda2
> watch cat /proc/mdstat


# Instal grub
> grub
grub> root (hd1,0)
grub> setup (hd1)
grub> root (hd0,0)
grub> setup (hd0)
grub> quit

> reboot


















































































> mount /dev/md0 /boot/