一、模拟磁盘设备
[root@localhost ~]# ls /dev/sd* # 查看添加的硬件----磁盘设备
/dev/sda /dev/sda1 /dev/sda2 /dev/sdb /dev/sdc
[root@localhost ~]# fdisk /dev/sdb # 分区 模拟出4块硬盘
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1): # 默认
First sector (2048-20971519, default 2048): #默认
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G # 添加1G
Partition 1 of type Linux and of size 1 GiB is set
操作同上共分了四个区 /dev/sdb{1,2,3,4} 当做四块硬盘使用
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0e220a08
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
/dev/sdb2 2099200 4196351 1048576 83 Linux
/dev/sdb3 4196352 6293503 1048576 83 Linux
/dev/sdb4 6293504 8390655 1048576 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# fdisk /dev/sdc # 分区模拟出4块硬盘
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G
Partition 1 of type Linux and of size 1 GiB is set
同上 分四个区 /dev/sdc{1,2,3,4} 当做4块硬盘使用
Device Boot Start End Blocks Id System
/dev/sdc1 2048 2099199 1048576 83 Linux
/dev/sdc2 2099200 4196351 1048576 83 Linux
/dev/sdc3 4196352 6293503 1048576 83 Linux
/dev/sdc4 6293504 8390655 1048576 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# ls /dev/sd*
/dev/sda /dev/sda2 /dev/sdb1 /dev/sdb3 /dev/sdc /dev/sdc2 /dev/sdc4
/dev/sda1 /dev/sdb /dev/sdb2 /dev/sdb4 /dev/sdc1 /dev/sdc3
二、创建RAID 5
mdadm 命令
选项
-C 创建软RAID
-l 指定RAID级别
-n 指定磁盘的个数
-x 指定备用设备的个数
-a 添加磁盘
-r 移除磁盘（热）
-v 显示详细信息
-s 扫描配置文件
-S 停止阵列 释放
-A 激活，加载 Assemble
-f 设为故障盘
[root@localhost ~]# mdadm -C /dev/md5 -l 5 -n 3 -x 1 /dev/sdb{1,2,3,4} # 创建raid 5
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Jun 19 21:00:53 2016
Raid Level : raid5
Array Size : 2095104 (2046.34 MiB 2145.39 MB)
Used Dev Size : 1047552 (1023.17 MiB 1072.69 MB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Jun 19 21:00:59 2016
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Name : localhost.localdomain:5 (local to host localhost.localdomain)
UUID : 467e61c9:1ddfd1c6:51c27a22:bb7d160c
Events : 18
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 18 1 active sync /dev/sdb2
4 8 19 2 active sync /dev/sdb3
3 8 20 - spare /dev/sdb4
[root@localhost ~]# ls /dev/md*
/dev/md5
[root@localhost ~]# fdisk /dev/md5
Device Boot Start End Blocks Id System
/dev/md5p1 2048 2099199 1048576 83 Linux
/dev/md5p2 2099200 4190207 1045504 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# mkfs.xfs /dev/md5p1 && mkfs.xfs /dev/md5p2
[root@localhost ~]# echo $?
0
[root@localhost ~]# mkdir /opt/raid{5_1,5_2}
[root@localhost ~]# blkid /dev/md*
/dev/md5: PTTYPE="dos"
/dev/md5p1: UUID="f1354f72-bbe5-4364-9ade-576d95d4c812" TYPE="xfs"
/dev/md5p2: UUID="d403dca4-6f77-411e-a519-b0536a8867e7" TYPE="xfs"
[root@localhost ~]# echo "UUID="f1354f72-bbe5-4364-9ade-576d95d4c812" /opt/raid5_1 xfs defaults 0 0" >> /etc/fstab
[root@localhost ~]# echo "UUID="d403dca4-6f77-411e-a519-b0536a8867e7" /opt/raid5_2 xfs defaults 0 0" >> /etc/fstab
[root@localhost ~]# tail -3 !$
tail -3 /etc/fstab
/dev/sr0 /mnt iso9660 defaults 0 0
UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0
UUID=d403dca4-6f77-411e-a519-b0536a8867e7 /opt/raid5_2 xfs defaults 0 0
[root@localhost ~]# mount -a
[root@localhost ~]# cp /etc/passwd /opt/raid5_1
[root@localhost ~]# cp /etc/passwd /opt/raid5_2
[root@localhost ~]# cp -r /etc /opt/raid5_1
[root@localhost ~]# cp -r /etc /opt/raid5_2
[root@localhost ~]# ls /opt/raid*
/opt/raid5_1:
etc passwd
/opt/raid5_2:
etc passwd
[root@localhost ~]# echo "DEVICES /dev/sdb1 /dev/sdb2 /dev/sdb3 /dev/sdb4" >> /etc/mdadm.conf
[root@localhost ~]# mdadm -Evs >> /etc/mdadm.conf
[root@localhost ~]# mount -a
[root@localhost ~]# tail -3 /etc/fstab
/dev/sr0 /mnt iso9660 defaults 0 0
UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0
UUID=d403dca4-6f77-411e-a519-b0536a8867e7 /opt/raid5_2 xfs defaults 0 0
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/md5p1 1018M 68M 951M 7% /opt/raid5_1
/dev/md5p2 1018M 68M 951M 7% /opt/raid5_2
[root@localhost ~]#
三、Raid 性能测试 （RAID 5 写入速度比普通磁盘块）
[root@localhost ~]# time dd if=/dev/zero of=txt bs=1M count=20
real 0m0.197s
user 0m0.001s
sys 0m0.180s
[root@localhost ~]# cd /opt/raid5_1
[root@localhost raid5_1]# time dd if=/dev/zero of=txt bs=1M count=20
real 0m0.102s
user 0m0.000s
sys 0m0.033s
四、RAID 故障模拟
[root@localhost ~]# mdadm /dev/md5 -f /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md5
此时可以动态查看一下
[root@localhost ~]# watch -n 1 cat /proc/mdstat
[root@localhost ~]# mdadm --detail /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Jun 19 21:00:53 2016
Raid Level : raid5
Array Size : 2095104 (2046.34 MiB 2145.39 MB)
Used Dev Size : 1047552 (1023.17 MiB 1072.69 MB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Jun 19 22:43:16 2016
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : localhost.localdomain:5 (local to host localhost.localdomain)
UUID : 467e61c9:1ddfd1c6:51c27a22:bb7d160c
Events : 37
Number Major Minor RaidDevice State
3 8 20 0 active sync /dev/sdb4
1 8 18 1 active sync /dev/sdb2
4 8 19 2 active sync /dev/sdb3
0 8 17 - faulty /dev/sdb1
[root@localhost ~]# mdadm -r /dev/md5 /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md5
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdb2[1] sdb3[4] sdb4[3]
2095104 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>
[root@localhost ~]# mdadm -a /dev/md5 /dev/sdc1
mdadm: added /dev/sdc1
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdc1[5](S) sdb2[1] sdb3[4] sdb4[3]
2095104 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>
[root@localhost ~]# diff /etc/passwd /opt/raid5_1/passwd
[root@localhost ~]# echo "DEVICE /dev/sdb2 /dev/sdb3 /dev/sdb4 /dev/sdc1" > /etc/mdadm.conf
[root@localhost ~]# mdadm -Evs >> !$
mdadm -Evs >> /etc/mdadm.conf
五、删除RAID设备
[root@localhost ~]# umount /opt/raid5_1
[root@localhost ~]# umount /opt/raid5_2
[root@localhost ~]# mdadm -Ss
[root@localhost ~]# rm -rf /etc/mdadm.conf
[root@localhost ~]# rm -rf /opt/raid5_1
[root@localhost ~]# rm -rf /opt/raid5_2
[root@localhost ~]# vim /etc/fstab #删除开机RAID挂载项
[root@localhost ~]# mdadm --misc --zero-superblock /dev/sdb1
[root@localhost ~]# mdadm --misc --zero-superblock /dev/sdb2
[root@localhost ~]# mdadm --misc --zero-superblock /dev/sdb3
[root@localhost ~]# mdadm --misc --zero-superblock /dev/sdb4
[root@localhost ~]# mdadm --misc --zero-superblock /dev/sdc1
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 10G 3.2G 6.9G 32% /
devtmpfs 898M 0 898M 0% /dev
tmpfs 913M 84K 913M 1% /dev/shm
tmpfs 913M 8.9M 904M 1% /run
tmpfs 913M 0 913M 0% /sys/fs/cgroup
/dev/sr0 3.8G 3.8G 0 100% /mnt
/dev/sda1 497M 158M 340M 32% /boot
tmpfs 183M 16K 183M 1% /run/user/42
tmpfs 183M 0 183M 0% /run/user/0
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
unused devices: <none>
[root@localhost ~]# mdadm --detail /dev/md5
mdadm: cannot open /dev/md5: No such file or directory本文出自 “树袋飘零” 博客，请务必保留此出处http://shudaipiaoling.blog.51cto.com/454831/1790904
原文地址：http://shudaipiaoling.blog.51cto.com/454831/1790904
