====== ソフトウェアraid構築 ======

下記のディスクでストライピングする場合

/dev/xvdb
/dev/xvdc

===== fdiskでRAIDパーティション作成 =====

/dev/xvdb、/dev/xvdc 両方で行う。

<code console>
# fdisk /dev/xvdb
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1):  
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): 
Using default value 2610

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): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
</code>

===== mdadm コマンドで RAID アレイを作成 =====

<code console>
# mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/xvdb /dev/xvdc
mdadm: /dev/xvdb appears to be part of a raid array:
    level=raid0 devices=2 ctime=Fri Mar 13 11:16:37 2015
mdadm: partition table exists on /dev/xvdb but will be lost or
       meaningless after creating array
mdadm: /dev/xvdc appears to be part of a raid array:
    level=raid0 devices=2 ctime=Fri Mar 13 11:16:37 2015
mdadm: partition table exists on /dev/xvdc but will be lost or
       meaningless after creating array
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
</code>

|--level=RAID|Level RAID レベルを指定する。|
|--raid-devices=|RAIDアレイを構成するデバイスの数|


===== 状態確認 =====

<code>
# cat /proc/mdstat 
Personalities : [raid0] 
md0 : active raid0 xvdc[1] xvdb[0]
      41942016 blocks super 1.2 512k chunks
</code>

===== マウント =====

<code>
# mkfs -t ext4 /dev/md0
# mount /dev/md0 /mnt
# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      18102140   1250540  15932048   8% /
tmpfs                   248728         0    248728   0% /dev/shm
/dev/xvda1              495844     96379    373865  21% /boot
/dev/md0              41283904    180284  39006520   1% /mnt
</code>

===== RAID アレイを解除 =====

<code>
# umount /mnt
# mdadm --stop /dev/md0
</code>