利用mdadm工具构建RAID 0/1/5/6/10磁盘阵列实战（超详细）

Dara ·

更新时间:2024-09-21

· 933 次阅读

Mdadm介绍：

mdadm是multiple devices admin的简称，它是Linux下的一款标准的软件 RAID 管理工具。

mdadm能够诊断、监控和收集详细的阵列信息。 mdadm是一个单独集成化的程序而不是一些分散程序的集合，因此对不同RAID管理命令有共通的语法。 mdadm能够执行几乎所有的功能而不需要配置文件。(也没有默认的配置文件）**

在linux系统中目前以MD(Multiple Devices)虚拟块设备的方式实现软件RAID,利用多个底层的块设备虚拟出一个新的虚拟设备,并且利用条带化(stripping)技术将数据块均匀分布到多个磁盘上来提高虚拟设备的读写性能,利用不同的数据冗祭算法来保护用户数据不会因为某个块设备的故障而完全丢失,而且还能在设备被替换后将丢失的数据恢复到新的设备上。

目前MD支持linear,multipath,raid0(stripping),raid1(mirror),raid4,raid5,raid6,raid10等不同的冗余级别和级成方式,当然也能支持多个RAID陈列的层叠组成raid1 0,raid5 1等类型的陈列。

环境介绍：

CentOS 7.5-Minimal
VMware Workstation 15
mdadm工具
六块磁盘：sdb sdc sdd sde sdf sdg

常用参数：

参数	作用
-a	添加磁盘
-n	指定设备数量
-l	指定RAID级别
-C	创建
-v	显示过程
-f	模拟设备损坏
-r	移除设备
-Q	查看摘要信息
-D	查看详细信息
-S	停止RAID磁盘阵列
-x	指定空闲盘（热备磁盘）个数，空闲盘（热备磁盘）能在工作盘损坏后自动顶替

mdadm工具指令基本格式：

mdadm -C -v 目录 -l 级别 -n 磁盘数量设备路径

查看RAID阵列方法：

cat /proc/mdstat        //查看状态
mdadm -D 目录           //查看详细信息

1.虚拟机磁盘准备
在这里插入图片描述
2.查看新增的磁盘

[root@localhost ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0    1G  0 part /boot
└─sda2            8:2    0   19G  0 part 
  ├─centos-root 253:0    0   17G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   20G  0 disk  -新
sdc               8:32   0   20G  0 disk  -新
sdd               8:48   0   20G  0 disk  -新
sde               8:64   0   20G  0 disk  -新
sdf               8:80   0   20G  0 disk  -新
sdg               8:96   0   10G  0 disk  -新
sr0              11:0    1  906M  0 rom

3.安装madam工具

[root@localhost ~]# yum -y install mdadm

更改磁盘分区格式：

分区格式需改为fd

****************************************
[root@localhost ~]# fdisk /dev/sdb     //修改sdb磁盘分区
...
命令(输入 m 获取帮助)：n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): 
Using default response p
分区号 (1-4，默认 1)：
起始 扇区 (2048-41943039，默认为 2048)：
将使用默认值 2048
Last 扇区, +扇区 or +size{K,M,G} (2048-41943039，默认为 41943039)：
将使用默认值 41943039
分区 1 已设置为 Linux 类型，大小设为 20 GiB
命令(输入 m 获取帮助)：t
已选择分区 1
Hex 代码(输入 L 列出所有代码)：fd
已将分区“Linux raid autodetect”的类型更改为“Linux raid autodetect”
命令(输入 m 获取帮助)：p
磁盘 /dev/sdb：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0xf056a1fe
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    41943039    20970496   fd  Linux raid autodetect
命令(输入 m 获取帮助)：w
The partition table has been altered!
Calling ioctl() to re-read partition table.
正在同步磁盘。
****************************************
[root@localhost ~]# fdisk /dev/sdc     //修改sdc磁盘分区
命令(输入 m 获取帮助)：p
...
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048    41943039    20970496   fd  Linux raid autodetect
****************************************
[root@localhost ~]# fdisk /dev/sdd      //修改sdd磁盘分区
命令(输入 m 获取帮助)：p
...
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdd1            2048    41943039    20970496   fd  Linux raid autodetect 
****************************************
[root@localhost ~]# fdisk /dev/sde      //修改sde磁盘分区
命令(输入 m 获取帮助)：p
...
   设备 Boot      Start         End      Blocks   Id  System
/dev/sde1            2048    41943039    20970496   fd  Linux raid autodetect
****************************************
[root@localhost ~]# fdisk /dev/sdf     //修改sdf磁盘分区
命令(输入 m 获取帮助)：p 
...
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdf1            2048    41943039    20970496   fd  Linux raid autodetect
****************************************
[root@localhost ~]# fdisk /dev/sdg
命令(输入 m 获取帮助)：p 
...
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdg1            2048    20971519    10484736   fd  Linux raid autodetect

RAID 0 实验

1.创建RAID 0

[root@localhost ~]# mdadm -C -v /dev/md0 -l 0 -n 2 /dev/sdb1 /dev/sdc1
 //在/dev/md0目录下将sdb1与sdc1两块磁盘创建为RAID级别为0，磁盘数为2的RAID0阵列
[root@localhost ~]# cat /proc/mdstat    //查看RAID 0
Personalities : [raid0] 
md0 : active raid0 sdc1[1] sdb1[0]
      41906176 blocks super 1.2 512k chunks
unused devices: 
[root@localhost ~]# mdadm -D /dev/md0   //查看RAID0详细信息
/dev/md0:
           Version : 1.2
     Creation Time : Tue Apr 21 15:55:29 2020
        Raid Level : raid0
        Array Size : 41906176 (39.96 GiB 42.91 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 15:55:29 2020
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0
        Chunk Size : 512K
Consistency Policy : none
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : 4b439b50:63314c34:0fb14c51:c9930745
            Events : 0
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1

2.格式化分区

[root@localhost ~]# mkfs.xfs /dev/md0 
meta-data=/dev/md0               isize=512    agcount=16, agsize=654720 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=10475520, imaxpct=25
         =                       sunit=128    swidth=256 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=5120, version=2
         =                       sectsz=512   sunit=8 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
[root@localhost ~]# blkid /dev/md0 
/dev/md0: UUID="13a0c896-5e79-451f-b6f1-b04b79c1bc40" TYPE="xfs"

3.格式化后挂载

[root@localhost ~]# mkdir /raid0      //创建挂载目录
[root@localhost ~]# mount /dev/md0 /raid0/   //将/dev/md0挂载到/raid0
[root@localhost ~]# df -h      //查看挂载是否成功
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   17G   11G  6.7G   61% /
devtmpfs                 1.1G     0  1.1G    0% /dev
tmpfs                    1.1G     0  1.1G    0% /dev/shm
...
/dev/md0                  40G   33M   40G    1% /raid0

RAID 1 实验

1.创建RAID 1

[root@localhost ~]# mdadm -C -v /dev/md1 -l 1 -n 2 /dev/sdd1 /dev/sde1 -x 1 /dev/sdb1 
  //在/dev/md1目录下将sdd1与sde1两块磁盘创建为RAID级别为1，磁盘数为2
  的RAID1磁盘阵列并将sdd1作为备用磁盘
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
mdadm: /dev/sdb1 appears to be part of a raid array:
       level=raid0 devices=2 ctime=Tue Apr 21 15:55:29 2020
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md1 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.

2.查看RAID 1状态

[root@localhost ~]# cat /proc/mdstat 
Personalities : [raid0] [raid1] 
md1 : active raid1 sdb1[2](S) sde1[1] sdd1[0]
      20953088 blocks super 1.2 [2/2] [UU]
      [==========>..........]  resync = 54.4% (11407360/20953088) finish=0.7min speed=200040K/sec
unused devices: 
[root@localhost ~]# mdadm -D /dev/md1 
/dev/md1:
           Version : 1.2
     Creation Time : Tue Apr 21 16:11:16 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:12:34 2020
             State : clean, resyncing 
    Active Devices : 2
   Working Devices : 3
    Failed Devices : 0
     Spare Devices : 1
Consistency Policy : resync
     Resync Status : 77% complete
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 98b76e6e:b6390011:26a822a8:3dcc4cc9
            Events : 12
    Number   Major   Minor   RaidDevice State
       0       8       49        0      active sync   /dev/sdd1
       1       8       65        1      active sync   /dev/sde1
       2       8       17        -      spare   /dev/sdb1

3.格式化并挂载

[root@localhost ~]# mkfs.xfs /dev/md1 
[root@localhost ~]# blkid /dev/md1
/dev/md1: UUID="18a8f33b-1bb6-43c2-8dfc-2b21a871961a" TYPE="xfs"
[root@localhost ~]# mkdir /raid1
[root@localhost ~]# mount /dev/md1 /raid1/
[root@localhost ~]# df -h
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   17G   11G  6.7G   61% /
...
/dev/md1                  20G   33M   20G    1% /raid1

4.模拟磁盘损坏

模拟损坏后查看RAID1阵列详细信息，发现/dev/sdb1自动替换了损坏的/dev/sdd1磁盘。

[root@localhost ~]# mdadm /dev/md1 -f /dev/sdd1
[root@localhost ~]# mdadm -D /dev/md1   //查看
/dev/md1:
           Version : 1.2
     Creation Time : Tue Apr 21 16:11:16 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:29:38 2020
             State : clean, degraded, recovering //正在自动恢复
    Active Devices : 1
   Working Devices : 2      
    Failed Devices : 1     //已损坏的磁盘
     Spare Devices : 1    //备用设备数
Consistency Policy : resync
    Rebuild Status : 46% complete
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 98b76e6e:b6390011:26a822a8:3dcc4cc9
            Events : 26
    Number   Major   Minor   RaidDevice State
       2       8       17        0      spare rebuilding   /dev/sdb1
       1       8       65        1      active sync   /dev/sde1
       0       8       49        -      faulty   /dev/sdd1
****** 备用磁盘正在自动替换损坏的磁盘，等几分钟再查看RAID1阵列详细信息
[root@localhost ~]# mdadm -D /dev/md1 
/dev/md1:
           Version : 1.2
     Creation Time : Tue Apr 21 16:11:16 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:30:39 2020
             State : clean    //干净，已经替换成功了
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 1     //已损坏的磁盘
     Spare Devices : 0     //备用设备数为0了
Consistency Policy : resync
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 98b76e6e:b6390011:26a822a8:3dcc4cc9
            Events : 36
    Number   Major   Minor   RaidDevice State
       2       8       17        0      active sync   /dev/sdb1
       1       8       65        1      active sync   /dev/sde1
       0       8       49        -      faulty   /dev/sdd1

5.移除损坏的磁盘

[root@localhost ~]# mdadm -r /dev/md1 /dev/sdd1
mdadm: hot removed /dev/sdd1 from /dev/md1
[root@localhost ~]# mdadm -D /dev/md1 
/dev/md1:
           Version : 1.2
     Creation Time : Tue Apr 21 16:11:16 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:38:32 2020
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0     //因为我们已经移除了，所以这里已经没有显示了
     Spare Devices : 0
Consistency Policy : resync
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 98b76e6e:b6390011:26a822a8:3dcc4cc9
            Events : 37
    Number   Major   Minor   RaidDevice State
       2       8       17        0      active sync   /dev/sdb1
       1       8       65        1      active sync   /dev/sde1

6.添加新磁盘到RAID1阵列：

[root@localhost ~]# mdadm -a /dev/md1 /dev/sdc1  
     //将/dev/sdc1磁盘添加为RAID1阵列的备用设备
mdadm: added /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md1 
/dev/md1:
           Version : 1.2
     Creation Time : Tue Apr 21 16:11:16 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:40:20 2020
             State : clean 
    Active Devices : 2
   Working Devices : 3
    Failed Devices : 0
     Spare Devices : 1   //刚添加了一块新磁盘，备用磁盘这里已经有显示
Consistency Policy : resync
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 98b76e6e:b6390011:26a822a8:3dcc4cc9
            Events : 38
    Number   Major   Minor   RaidDevice State
       2       8       17        0      active sync   /dev/sdb1
       1       8       65        1      active sync   /dev/sde1
       3       8       33        -      spare   /dev/sdc1

注意：

新增加的硬盘需要与原硬盘大小一致。如果原有阵列缺少工作磁盘（如raid1只有一块在工作，raid5只有2块在工作），这时新增加的磁盘直接变为工作磁盘，如果原有阵列工作正常，则新增加的磁盘为热备磁盘。 7.停止RAID阵列

要停止阵列，需要先将挂载的RAID先取消挂载才可以停止阵列，并且停止阵列之后会自动删除创建阵列的目录。

[root@localhost ~]# umount /dev/md1 
[root@localhost ~]# df -h
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   17G   11G  6.7G   61% /
devtmpfs                 1.1G     0  1.1G    0% /dev
tmpfs                    1.1G     0  1.1G    0% /dev/shm
tmpfs                    1.1G  9.7M  1.1G    1% /run
tmpfs                    1.1G     0  1.1G    0% /sys/fs/cgroup
/dev/sda1               1014M  130M  885M   13% /boot
overlay                   17G   11G  6.7G   61% /var/lib/docker/overlay2/2131dc663296fd193837265e88fa5c9c62b9bfd924303381cea8b4c39c652c84/merged
shm                       64M     0   64M    0% /var/lib/docker/containers/436f7e6619c1805553ea71d800fd49ab08843cef6ed162acb35b4c32064ea449/mounts/shm
tmpfs                    211M     0  211M    0% /run/user/0
[root@localhost ~]# mdadm -S /dev/md1  
mdadm: stopped /dev/md1
[root@localhost ~]# ls /dev/md1
ls: 无法访问/dev/md1: 没有那个文件或目录

RAID 5 实验

1.创建RAID 5

[root@localhost ~]# mdadm -C -v /dev/md5 -l 5 -n 3 /dev/sdb1 /dev/sdc1 /dev/sdd1 -x 1 /dev/sde1 
//在/dev/md5目录下将sdb1、sdc1、sdd1三块磁盘创建为RAID级别为5，磁盘
数为3的RAID5磁盘阵列并将sde1作为备用磁盘
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: /dev/sdb1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Tue Apr 21 16:11:16 2020
mdadm: /dev/sdc1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Tue Apr 21 16:11:16 2020
mdadm: /dev/sdd1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Tue Apr 21 16:11:16 2020
mdadm: /dev/sde1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Tue Apr 21 16:11:16 2020
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md5 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.

2.查看RAID 5阵列信息

[root@localhost ~]# cat /proc/mdstat 
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] 
md5 : active raid5 sdd1[4] sde1[3](S) sdc1[1] sdb1[0]
      41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: 
[root@localhost ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Tue Apr 21 16:56:09 2020
        Raid Level : raid5
        Array Size : 41906176 (39.96 GiB 42.91 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 16:59:56 2020
             State : clean 
    Active Devices : 3
   Working Devices : 4    
    Failed Devices : 0
     Spare Devices : 1    //备用设备数1
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:5  (local to host localhost.localdomain)
              UUID : 422363cb:e7fd4d3a:aaf61344:9bdd00b3
            Events : 18
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1
       4       8       49        2      active sync   /dev/sdd1
       3       8       65        -      spare   /dev/sde1

3.模拟磁盘损坏

[root@localhost ~]# mdadm -f /dev/md5 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md5   //提示sdb1已损坏
[root@localhost ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Tue Apr 21 16:56:09 2020
        Raid Level : raid5
        Array Size : 41906176 (39.96 GiB 42.91 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 17:04:36 2020
             State : clean, degraded, recovering   //正在自动替换
    Active Devices : 2
   Working Devices : 3
    Failed Devices : 1
     Spare Devices : 1
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
    Rebuild Status : 16% complete
              Name : localhost.localdomain:5  (local to host localhost.localdomain)
              UUID : 422363cb:e7fd4d3a:aaf61344:9bdd00b3
            Events : 22
    Number   Major   Minor   RaidDevice State
       3       8       65        0      spare rebuilding   /dev/sde1
       1       8       33        1      active sync   /dev/sdc1
       4       8       49        2      active sync   /dev/sdd1
       0       8       17        -      faulty   /dev/sdb1
**************************
[root@localhost ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Tue Apr 21 16:56:09 2020
        Raid Level : raid5
        Array Size : 41906176 (39.96 GiB 42.91 GB)
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 17:07:58 2020
             State : clean     //自动替换成功
    Active Devices : 3
   Working Devices : 3
    Failed Devices : 1     //损坏磁盘数为1
     Spare Devices : 0     //备用磁盘数为0，因为已经替换
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:5  (local to host localhost.localdomain)
              UUID : 422363cb:e7fd4d3a:aaf61344:9bdd00b3
            Events : 37
    Number   Major   Minor   RaidDevice State
       3       8       65        0      active sync   /dev/sde1
       1       8       33        1      active sync   /dev/sdc1
       4       8       49        2      active sync   /dev/sdd1
       0       8       17        -      faulty   /dev/sdb1

4.格式化并挂载

[root@localhost ~]# mkdir /raid5
[root@localhost ~]# mkfs.xfs /dev/md5
[root@localhost ~]# mount /dev/md5 /raid5/
[root@localhost ~]# df -h
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   17G   11G  6.7G   61% /
...
/dev/md5                  40G   33M   40G    1% /raid5

5.停止阵列

[root@localhost ~]# mdadm -S /dev/md5 
mdadm: stopped /dev/md5

RAID 6 实验

1.创建RAID 6阵列

[root@localhost ~]# mdadm -C -v /dev/md6 -l 6 -n 4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 -x 2 /dev/sdf1 /dev/sdg1 
//在/dev/md6目录下将sdb1、sdc1、sdd1、sde1四块磁盘创建为RAID级别
为6，磁盘数为4的RAID6磁盘阵列并将sdf1、sdg1作为备用磁盘
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: /dev/sdb1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:37:15 2020
mdadm: partition table exists on /dev/sdb1 but will be lost or
       meaningless after creating array
mdadm: /dev/sdc1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:37:15 2020
mdadm: /dev/sdd1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:37:15 2020
mdadm: /dev/sde1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:37:15 2020
mdadm: /dev/sdf1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:37:15 2020
mdadm: size set to 10467328K
mdadm: largest drive (/dev/sdb1) exceeds size (10467328K) by more than 1%
Continue creating array? y
mdadm: Fail create md6 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md6 started.

2.查看RAID 6阵列信息

[root@localhost ~]# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
md6 : active raid6 sdg1[5](S) sdf1[4](S) sde1[3] sdd1[2] sdc1[1] sdb1[0]
      20934656 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
unused devices: 
[root@localhost ~]# mdadm -D /dev/md6 
/dev/md6:
           Version : 1.2
     Creation Time : Tue Apr 21 17:54:25 2020
        Raid Level : raid6
        Array Size : 20934656 (19.96 GiB 21.44 GB)
     Used Dev Size : 10467328 (9.98 GiB 10.72 GB)
      Raid Devices : 4
     Total Devices : 6
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 17:58:16 2020
             State : clean 
    Active Devices : 4
   Working Devices : 6
    Failed Devices : 0
     Spare Devices : 2
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:6  (local to host localhost.localdomain)
              UUID : 9a5c470e:eb95d0b4:2a213dac:f0fd3315
            Events : 17
    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
       3       8       65        3      active sync   /dev/sde1
       4       8       81        -      spare   /dev/sdf1
       5       8       97        -      spare   /dev/sdg1

3.模拟磁盘损坏（同时损坏两块）

[root@localhost ~]# mdadm -f /dev/md6 /dev/sdb1   //sdb1损坏
mdadm: set /dev/sdb1 faulty in /dev/md6
[root@localhost ~]# mdadm -f /dev/md6 /dev/sdc1   //sdc1损坏
mdadm: set /dev/sdc1 faulty in /dev/md6
[root@localhost ~]# mdadm -D /dev/md6    //查看RAID6阵列状态
/dev/md6:
           Version : 1.2
     Creation Time : Tue Apr 21 17:54:25 2020
        Raid Level : raid6
        Array Size : 20934656 (19.96 GiB 21.44 GB)
     Used Dev Size : 10467328 (9.98 GiB 10.72 GB)
      Raid Devices : 4
     Total Devices : 6
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 18:01:46 2020
             State : clean, degraded, recovering   //正在替换
    Active Devices : 2
   Working Devices : 4
    Failed Devices : 2     //损坏磁盘数2块
     Spare Devices : 2    //备用设备数2 
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
    Rebuild Status : 19% complete
              Name : localhost.localdomain:6  (local to host localhost.localdomain)
              UUID : 9a5c470e:eb95d0b4:2a213dac:f0fd3315
            Events : 29
    Number   Major   Minor   RaidDevice State
       5       8       97        0      spare rebuilding   /dev/sdg1
       4       8       81        1      spare rebuilding   /dev/sdf1
       2       8       49        2      active sync   /dev/sdd1
       3       8       65        3      active sync   /dev/sde1
       0       8       17        -      faulty   /dev/sdb1
       1       8       33        -      faulty   /dev/sdc1
*****************************
[root@localhost ~]# mdadm -D /dev/md6 
/dev/md6:
           Version : 1.2
     Creation Time : Tue Apr 21 17:54:25 2020
        Raid Level : raid6
        Array Size : 20934656 (19.96 GiB 21.44 GB)
     Used Dev Size : 10467328 (9.98 GiB 10.72 GB)
      Raid Devices : 4
     Total Devices : 6
       Persistence : Superblock is persistent
       Update Time : Tue Apr 21 18:04:02 2020
             State : clean    //已自动替换
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 2
     Spare Devices : 0       //备用设备为0
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:6  (local to host localhost.localdomain)
              UUID : 9a5c470e:eb95d0b4:2a213dac:f0fd3315
            Events : 43
    Number   Major   Minor   RaidDevice State
       5       8       97        0      active sync   /dev/sdg1
       4       8       81        1      active sync   /dev/sdf1
       2       8       49        2      active sync   /dev/sdd1
       3       8       65        3      active sync   /dev/sde1
       0       8       17        -      faulty   /dev/sdb1
       1       8       33        -      faulty   /dev/sdc1

4.格式化并挂载

方法同上。

5.停止阵列

[root@localhost ~]# mdadm -S /dev/md6 
mdadm: stopped /dev/md6

RAID 10 实验

RAID 1+0是用两个RAID 1来创建。

1.创建两个RAID 1阵列

[root@localhost ~]# mdadm -C -v /dev/md1 -l 1 -n 2 /dev/sdb1 /dev/sdc1 
mdadm: /dev/sdb1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Wed Apr 22 00:47:05 2020
mdadm: partition table exists on /dev/sdb1 but will be lost or
       meaningless after creating array
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
mdadm: /dev/sdc1 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Wed Apr 22 00:47:05 2020
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md1 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.
[root@localhost ~]# mdadm -C -v /dev/md0 -l 1 -n 2 /dev/sdd1 /dev/sde1 
mdadm: /dev/sdd1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:54:25 2020
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
mdadm: /dev/sde1 appears to be part of a raid array:
       level=raid6 devices=4 ctime=Tue Apr 21 17:54:25 2020
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md0 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

2.查看两个RAID 1阵列信息

[root@localhost ~]# mdadm -D /dev/md1 
/dev/md1:
           Version : 1.2
     Creation Time : Wed Apr 22 00:48:19 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)  
                           *****第一个RAID 1容量20G*****
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
       Update Time : Wed Apr 22 00:50:21 2020
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0
Consistency Policy : resync
              Name : localhost.localdomain:1  (local to host localhost.localdomain)
              UUID : 95cd9b90:8dcbbbef:7974f3aa:d38d7f5b
            Events : 17
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Wed Apr 22 00:48:52 2020
        Raid Level : raid1
        Array Size : 20953088 (19.98 GiB 21.46 GB)
                  *****第二个RAID 1容量20G******
     Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
       Update Time : Wed Apr 22 00:50:44 2020
             State : clean, resyncing 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0
Consistency Policy : resync
     Resync Status : 96% complete
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : ae813945:1174d6cb:ad1e3a33:1303a7d3
            Events : 15
    Number   Major   Minor   RaidDevice State
       0       8       49        0      active sync   /dev/sdd1
       1       8       65        1      active sync   /dev/sde1

3.创建RAID 1+0阵列

[root@localhost ~]# mdadm -C -v /dev/md10 -l 0 -n 2 /dev/md1 /dev/md0 
mdadm: chunk size defaults to 512K
mdadm: Fail create md10 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md10 started.

4.查看RAID 1+0阵列信息

[root@localhost ~]# mdadm -D /dev/md10
/dev/md10:
           Version : 1.2
     Creation Time : Wed Apr 22 00:55:41 2020
        Raid Level : raid0
        Array Size : 41871360 (39.93 GiB 42.88 GB)
                     *****制作的RAID 1+0 容量40G*****
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
       Update Time : Wed Apr 22 00:55:41 2020
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0
        Chunk Size : 512K
Consistency Policy : none
              Name : localhost.localdomain:10  (local to host localhost.localdomain)
              UUID : 09a95fcb:c9a2ec94:4461c81e:a9a65c2f
            Events : 0
    Number   Major   Minor   RaidDevice State
       0       9        1        0      active sync   /dev/md1
       1       9        0        1      active sync   /dev/md0

作者：非著名运维

实战 mdadm raid

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