命令行操作RAID5

本文作者 szxsztszk ，其著作权归 szxsztszk 所有。

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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

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