Create software raid for Linux

1. First create new partition.

切割三個partitions完畢後，指定每個partition type為fd.( Linux raid auto)

Command (m for help): t
Partition number (1-4): 1
Hex code (type L to list codes): fd
fd  Linux raid auto
 
2. Copy file to /etc/raidtab
 在 /usr/share/doc/raidtools-1.00.3下有所有範例檔了。
Copy 其中一種sample到 /etc/raidtab
copy /usr/share/doc/raidtools-1.00.03/raid5.conf.sample /etc/raidtab
 
3. Edit /etc/raidtab (依實際情況修改)
 raiddev /dev/md0   (裝置名稱，預設是md0)
       raid-level    5       (Raid 5)
       nr-raid-disks 4 (共有幾個partition加入raid)
       nr-spare-disks      1  (Disk fail時，備用)
       persistent-superblock      1(開機能自動detect 到 partition)
       chunk-size    32   (寫進單一partition大小) 
       parity-algorithm    left-symmetric
       device        /dev/sdb1
       raid-disk     0           (raid partition從0開始)
       device        /dev/sdb2
       raid-disk     1
       device        /dev/sdb3
       raid-disk     2
        device       /dev/sdb4
       raid-disk     3
 
       device        /dev/sdc1 
       spare-disk    0            (spare的partition)
 
4. Edit完後 mkraid /dev/md0 就OK了。

5. 查看狀況:
cat /proc/mdstat

Personalities : [raid5]

read_ahead 1024 sectors

Event: 2                  

md0 : active raid5 sdb4[3] sdb3[2] sdb2[1] sdb1[0]

      2963520 blocks level 5, 4k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

 
6. 其它:
raidstart        啟動raid devices
raidstop         停止raid devices
raidhotadd      (新增HDD)
raidhotremove   (移除HDD)