1 新建三个分区
代码语言：txt复制[root@centos68 ~]# fdisk /dev/sdb
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 1 3917 31463271 5 Extended
/dev/sdb5 1 654 5253192 83 Linux
/dev/sdb6 655 1308 5253223 83 Linux
/dev/sdb7 1309 1962 5253223 83 Linux2 将分区类型修改为fd（Linux raid autodetect）
代码语言：txt复制Command (m for help): t
Partition number (1-7): 5
Hex code (type L to list codes): fd
Changed system type of partition 5 to fd (Linux raid autodetect)
Command (m for help): t
Partition number (1-7): 6
Hex code (type L to list codes): fd
Changed system type of partition 6 to fd (Linux raid autodetect)
Command (m for help): t
Partition number (1-7): 7
Hex code (type L to list codes): fd
Changed system type of partition 7 to fd (Linux raid autodetect)
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 1 3917 31463271 5 Extended
/dev/sdb5 1 654 5253192 fd Linux raid autodetect
/dev/sdb6 655 1308 5253223 fd Linux raid autodetect
/dev/sdb7 1309 1962 5253223 fd Linux raid autodetect保存退出
代码语言：txt复制Command (m for help): w
The partition table has been altered!强制重读磁盘分区表(多运行几次)
代码语言：txt复制[root@centos68 ~]# partx -a /dev/sdb3 新建空闲分区
代码语言：txt复制[root@centos68 ~]# fdisk /dev/sdb
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (1963-3917, default 1963):
Using default value 1963
Last cylinder, cylinders or size{K,M,G} (1963-3917, default 3917): 5G
Command (m for help): t
Partition number (1-8): 8
Hex code (type L to list codes): fd
Changed system type of partition 8 to fd (Linux raid autodetect)
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 1 3917 31463271 5 Extended
/dev/sdb5 1 654 5253192 fd Linux raid autodetect
/dev/sdb6 655 1308 5253223 fd Linux raid autodetect
/dev/sdb7 1309 1962 5253223 fd Linux raid autodetect
/dev/sdb8 1963 2616 5253223 fd Linux raid autodetect
Command (m for help): w
The partition table has been altered!
# 强制重读分区表
[root@centos68 ~]# partx -a /dev/sdb4 创建RAID-5
代码语言：txt复制[root@centos68 ~]# mdadm -C /dev/md0 -a yes -n 3 -x 1 -l 5 /dev/sdb{5,6,7,8}
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.查看数据同步过程
代码语言：txt复制[root@centos68 ~]# watch -n1 'cat /proc/mdstat'查看所有md类型设备的状态
代码语言：txt复制[root@centos68 ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb7[4] sdb8[3](S) sdb6[1] sdb5[0]
10498048 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>查看RAID详细信息
代码语言：txt复制[root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Thu Jun 25 03:49:10 2020
Raid Level : raid5
Array Size : 10498048 (10.01 GiB 10.75 GB)
Used Dev Size : 5249024 (5.01 GiB 5.38 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Thu Jun 25 03:53:07 2020
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0 (local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events : 18
Number Major Minor RaidDevice State
0 8 21 0 active sync /dev/sdb5
1 8 22 1 active sync /dev/sdb6
4 8 23 2 active sync /dev/sdb7
3 8 24 - spare /dev/sdb85 格式化分区
代码语言：txt复制[root@centos68 ~]# mke2fs -t ext4 /dev/md0查看
代码语言：txt复制[root@centos68 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_centos68-lv_root
50G 861M 46G 2% /
tmpfs 931M 0 931M 0% /dev/shm
/dev/sda1 477M 39M 413M 9% /boot
/dev/mapper/vg_centos68-lv_home
45G 52M 43G 1% /home
/dev/md0 9.8G 23M 9.3G 1% /data实现开机自动挂载
代码语言：txt复制[root@centos68 ~]# blkid /dev/md0
/dev/md0: UUID="e2303c17-62a6-4938-aa7a-d5b9c52ab4ea" TYPE="ext4"
# 建议使用UUID进行挂载或者LABEL卷标挂载
[root@centos68 ~]# tail -1 /etc/fstab
UUID=e2303c17-62a6-4938-aa7a-d5b9c52ab4ea /data defaults,acl 0 06 模拟坏盘
代码语言：txt复制[root@centos68 ~]# mdadm /dev/md0 -f /dev/sdb5
mdadm: set /dev/sdb5 faulty in /dev/md0查看备用盘同步过程
代码语言：txt复制[root@centos68 ~]# cat /proc/mdstat # 或者使用 watch -n1 'cat /proc/mdstat' 动态观察恢复过程
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb7[4] sdb8[3] sdb6[1] sdb5[0](F)
10498048 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
[=>...................] recovery = 6.8% (359808/5249024) finish=0.6min speed=119936K/sec
unused devices: <none>再次查看RAID详细信息
==备用盘sdb8已经顶替坏盘sdb5==
代码语言：txt复制[root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Thu Jun 25 03:49:10 2020
Raid Level : raid5
Array Size : 10498048 (10.01 GiB 10.75 GB)
Used Dev Size : 5249024 (5.01 GiB 5.38 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Thu Jun 25 04:07:21 2020
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0 (local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events : 37
Number Major Minor RaidDevice State
3 8 24 0 active sync /dev/sdb8
1 8 22 1 active sync /dev/sdb6
4 8 23 2 active sync /dev/sdb7
0 8 21 - faulty /dev/sdb57 模拟坏盘并观察数据是否正常访问
拷贝测试数据到RAID-5挂载点/data
代码语言：txt复制[root@centos68 ~]# cp /etc/passwd /data/
[root@centos68 ~]# ll /data/passwd
-rw-r--r--. 1 root root 887 Jun 25 04:13 /data/passwd
[root@centos68 ~]# cat /etc/passwd模拟坏盘/dev/sdb8，观察state状态
代码语言：txt复制[root@centos68 ~]# mdadm /dev/md0 -f /dev/sdb8
mdadm: set /dev/sdb8 faulty in /dev/md0
[root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Thu Jun 25 03:49:10 2020
Raid Level : raid5
Array Size : 10498048 (10.01 GiB 10.75 GB)
Used Dev Size : 5249024 (5.01 GiB 5.38 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Thu Jun 25 04:15:23 2020
State : clean, degraded # 降级运行模式
Active Devices : 2
Working Devices : 2
Failed Devices : 2
Spare Devices : 0
Layout : left-symmetric # 默认布局左对称
Chunk Size : 512K
Name : centos68:0 (local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events : 39
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 22 1 active sync /dev/sdb6
4 8 23 2 active sync /dev/sdb7
0 8 21 - faulty /dev/sdb5
3 8 24 - faulty /dev/sdb8测试数据是否正常访问
代码语言：txt复制[root@centos68 ~]# cd /data
[root@centos68 data]# cat passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin8 移除坏盘
代码语言：txt复制[root@centos68 data]# mdadm /dev/md0 -r /dev/sdb5
mdadm: hot removed /dev/sdb5 from /dev/md0
[root@centos68 data]# mdadm /dev/md0 -r /dev/sdb8
mdadm: hot removed /dev/sdb8 from /dev/md0
[root@centos68 data]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Thu Jun 25 03:49:10 2020
Raid Level : raid5
Array Size : 10498048 (10.01 GiB 10.75 GB)
Used Dev Size : 5249024 (5.01 GiB 5.38 GB)
Raid Devices : 3
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Thu Jun 25 04:19:05 2020
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0 (local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events : 45
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 22 1 active sync /dev/sdb6
4 8 23 2 active sync /dev/sdb79 添加磁盘
代码语言：txt复制[root@centos68 data]# mdadm /dev/md0 -a /dev/sdb5
mdadm: added /dev/sdb5查看数据同步过程
代码语言：txt复制[root@centos68 data]# watch -n1 'cat /proc/mdstat'
Every 1.0s: cat /proc/mdstat Thu Jun 25 04:23:04 2020
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb5[3] sdb7[4] sdb6[1]
10498048 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
[================>....] recovery = 82.0% (4309708/5249024) finish=0.1min speed=1
00386K/sec
unused devices: <none>参考文档：https://cloud.tencent.com/developer/article/1562726
