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): nPartition type: p primary (0 primary, 0 extended, 4 free) e extendedSelect (default p): pPartition number (1-4, default 1): # 默认First sector (2048-20971519, default 2048): #默认Using default value 2048Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G # 添加1GPartition 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): pDisk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk 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 LinuxCommand (m for help): wThe 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): nPartition type: p primary (0 primary, 0 extended, 4 free) e extendedSelect (default p): pPartition number (1-4, default 1): First sector (2048-20971519, default 2048): Using default value 2048Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1GPartition 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 LinuxCommand (m for help): wThe 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 metadatamdadm: 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 : 3Working 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 LinuxCommand (m for help): wThe 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 0UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0UUID=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 0UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0UUID=d403dca4-6f77-411e-a519-b0536a8867e7 /opt/raid5_2 xfs defaults 0 0[root@localhost ~]# df -hFilesystem 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=20real 0m0.197suser 0m0.001ssys 0m0.180s[root@localhost ~]# cd /opt/raid5_1[root@localhost raid5_1]# time dd if=/dev/zero of=txt bs=1M count=20real 0m0.102suser 0m0.000ssys 0m0.033s四、RAID 故障模拟[root@localhost ~]# mdadm /dev/md5 -f /dev/sdb1mdadm: 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 : 3Working 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/sdb1mdadm: hot removed /dev/sdb1 from /dev/md5[root@localhost ~]# cat /proc/mdstatPersonalities : [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: [root@localhost ~]# mdadm -a /dev/md5 /dev/sdc1mdadm: added /dev/sdc1[root@localhost ~]# cat /proc/mdstatPersonalities : [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: [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 -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/rhel-root 10G 3.2G 6.9G 32% /devtmpfs 898M 0 898M 0% /devtmpfs 913M 84K 913M 1% /dev/shmtmpfs 913M 8.9M 904M 1% /runtmpfs 913M 0 913M 0% /sys/fs/cgroup/dev/sr0 3.8G 3.8G 0 100% /mnt/dev/sda1 497M 158M 340M 32% /boottmpfs 183M 16K 183M 1% /run/user/42tmpfs 183M 0 183M 0% /run/user/0[root@localhost ~]# cat /proc/mdstatPersonalities : [raid6] [raid5] [raid4] unused devices: [root@localhost ~]# mdadm --detail /dev/md5mdadm: cannot open /dev/md5: No such file or directory