命令行操作raid5

RAID5:

mdadm是一个全新的raid管理工具,rhel LINUX版本 >= RHEL4.

要求:需要在三块硬盘上创建RAID5 并挂载到 /raid5disk 目录下!

先用fdisk -l 看一下三块磁盘的设备号,在这里就是

/dev/sdb 
/dev/sdc 
/dev/sdd

1. 首先在三块硬盘上分别创建一个分区!

# fdisk /dev/sdb
Command (m for help): n       按n创建新分区
Command action
e   extended
p   primary partition (1-4)     输入p 选择创建主分区
    
Partition number (1-4):          输入 1 创建第一个主分区
First cylinder (1-204, default1):   直接回车,选择分区开始柱面这里就从 1 开始
Last cylinder or +size or +sizeM or+sizeK (1-204, default 204): 

也是直接回车,最后一个柱面!我这里是204, 各人的硬盘大小不一样大,这里的值也不一样大! 这样就将硬盘1柱面到204柱面创建了第一个主分区!

          
Command (m for help): t       输入t 指定分区类型!

Selected partition 1
Hex code (type L to listcodes):

可以直接输入fd,指定分区类型就为Linux raid auto 也可以输入l看一下所有支持的分区类型! 我这里倒数第三个就是raid的分区类型代号为fd

     
Command (m for help): w             然后输入w写盘! 
The partition table has been altered!
Calling ioctl() to re-read partitiontable.
Syncing disks.

按照此步骤在另外的两块磁盘上做同样的操作! 全部做完后,运行 fdisk -l 应该可以看到如下信息!

          
   Disk /dev/sdb: 214 MB, 214748160 bytes
64 heads, 32 sectors/track, 204 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
   Device Boot     Start         End     Blocks   Id  System
/dev/sdb1              1         204     208880   fd  Linux raid autodetect
Disk /dev/sdc: 214 MB, 214748160 bytes
64 heads, 32 sectors/track, 204 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
   Device Boot     Start         End     Blocks   Id  System
/dev/sdc1              1         204     208880   fd  Linux raid autodetect
Disk /dev/sdd: 214 MB, 214748160 bytes
64 heads, 32 sectors/track, 204 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
   Device Boot     Start         End     Blocks   Id  System
/dev/sdd1              1         204     208880   fd  Linux raid autodetect

看到上面三个磁盘上分别建了一个分区,分区大小都一样! 然后再运行

#mdadm -Cv /dev/md0 -l5 -n3 /dev/sdb1 /dev/sdc1 /dev/sdd1    

这里就在三个分区上创建了raid5 软件陈列, 新的分区设备号为md0 然后格式化一下md0分区

[root@localhost ~]# mkfs.ext3 /dev/md0
mke2fs 1.35 (28-Feb-2004)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
104448 inodes, 417536 blocks
20876 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67633152
51 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks: 
        8193, 24577, 40961, 57345, 73729, 204801,221185, 401409
Writing inode tables: done                          
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every29 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

根据分区大小一样,这里需要的时间也会不一样!

然后在 #mkdir /raid5disk 在/上建一个目录raid5disk 然后用mount 将md0挂上去! #mount /dev/md0 /raid5disk/ 好了,试试到raiddisk目录建几个文件! 为了让系统重新启动后自动挂载,可以修改一下/etc/fstab文件,添加一行! /dev/md0 /raid5disk auto defaults 0 0 这样系统重新启动后会自动将/dev/md0挂接到 /raid5disk目录下! 好了!一切OK! 再查看一下md0的状态!

[root@localhost ~]# mdadm -D /dev/md0 /dev/md0:

      Version : 00.90.01
Creation Time : Tue Feb 28 22:10:41 2006
   Raid Level : raid5
   Array Size : 417536 (407.75 MiB 427.56 MB)
  Device Size : 208768 (203.88 MiB 213.78 MB)
 Raid Devices : 3
Total Devices : 3

Preferred Minor : 0

  Persistence : Superblock is persistent
  Update Time : Tue Feb 28 22:17:55 2006
        State : clean

Active Devices : 3 Working Devices : 3 Failed Devices : 0

Spare Devices : 0
       Layout :left-symmetric
   Chunk Size : 64K
  Number   Major  Minor   RaidDevice State
  0       8       17       0      active sync  /dev/sdb1
  1       8       33       1      active sync  /dev/sdc1
  2       8       49       2      active sync  /dev/sdd1
         UUID : 70fc89c1:ef191858:784578eb:81603b8d
       Events : 0.48

一切正常!

备注:

删除已有的software raid:

1.stop /dev/mdX: mdadm -S /dev/mdX 或者rm /dev/mdX

2.del/etc/mdadm.conf

3.del raid mount in /etc/fstab and autofs

4.del raid part use fdisk or parted