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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