Linux 常见 RAID 及软 RAID 创建

我不是女神ヾ 2023-06-02 07:44 20阅读 0赞

![CentOS-Logo][]

`RAID`可以大幅度的提高磁盘性能，以及可靠性，这么好的技术怎么能不掌握呢！此篇介绍一些常见`RAID`，及其在`Linux`上的`软RAID`创建方法。

--------------------

# mdadm #

*  创建软`RAID`

mdadm -C -v /dev/创建的设备名 -l级别 -n数量 添加的磁盘 [-x数量 添加的热备份盘]

`-C`：创建一个新的阵列`--create`  
`-v`：显示细节`--verbose`  
`-l`：设定RAID级别`--level=`  
`-n`：指定阵列中可用`device`数目`--raid-devices=`  
`-x`：指定初始阵列的富余`device`数目`--spare-devices=`，空闲盘（热备磁盘）能在工作盘损坏后自动顶替

*  查看详细信息

mdadm -D /dev/设备名

`-D`：打印一个或多个`md device`的详细信息`--detail`

*  查看`RAID`的状态

cat /proc/mdstat

*  模拟损坏

mdadm -f /dev/设备名 磁盘

`-f`：模拟损坏`fail`

*  移除损坏

mdadm -r /dev/设备名 磁盘

`-r`：移除`remove`

*  添加新硬盘作为热备份盘

mdadm -a /dev/设备名 磁盘

`-a`：添加`add`

--------------------

# RAID0 #

`RAID0`俗称条带，它将两个或多个硬盘组成一个逻辑硬盘，容量是所有硬盘之和，因为是多个硬盘组合成一个，故可并行写操作，写入速度提高，但此方式硬盘数据没有冗余，没有容错，一旦一个物理硬盘损坏，则所有数据均丢失。因而，`RAID0`适合于对数据量大，但安全性要求不高的场景，比如音像、视频文件的存储等。

![RAID0][]

**实验**：`RAID0`创建，格式化，挂载使用。

1.添加`2`块`20G`的硬盘，分区，类型`ID`为`fd`。

[root@localhost ~]# fdisk -l | grep raid
    /dev/sdb1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sdc1            2048    41943039    20970496   fd  Linux raid autodetect

2.创建`RAID0`。

[root@localhost ~]# mdadm -C -v /dev/md0 -l0 -n2 /dev/sd{b,c}1
    mdadm: chunk size defaults to 512K
    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.

3.查看`raidstat`状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid0]
    md0 : active raid0 sdc1[1] sdb1[0]
          41906176 blocks super 1.2 512k chunks
    
    unused devices: <none>

4.查看`RAID0`的详细信息。

[root@localhost ~]# mdadm -D /dev/md0
    /dev/md0:
               Version : 1.2
         Creation Time : Sun Aug 25 15:28:13 2019
            Raid Level : raid0
            Array Size : 41906176 (39.96 GiB 42.91 GB)
          Raid Devices : 2
         Total Devices : 2
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 15:28:13 2019
                 State : clean
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
            Chunk Size : 512K
    
    Consistency Policy : none
    
                  Name : localhost:0  (local to host localhost)
                  UUID : 7ff54c57:b99a59da:6b56c6d5:a4576ccf
                Events : 0
    
        Number   Major   Minor   RaidDevice State
           0       8       17        0      active sync   /dev/sdb1
           1       8       33        1      active sync   /dev/sdc1

5.格式化。

[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

6.挂载使用。

[root@localhost ~]# mkdir /mnt/md0
    [root@localhost ~]# mount /dev/md0 /mnt/md0/
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G 1013M   16G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  904M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/md0                xfs        40G   33M   40G   1% /mnt/md0

--------------------

# RAID1 #

`RAID1`俗称镜像，它最少由两个硬盘组成，且两个硬盘上存储的数据均相同，以实现数据冗余。`RAID1`读操作速度有所提高，写操作理论上与单硬盘速度一样，但由于数据需要同时写入所有硬盘，实际上稍为下降。容错性是所有组合方式里最好的，只要有一块硬盘正常，则能保持正常工作。但它对硬盘容量的利用率则是最低，只有`50%`，因而成本也是最高。`RAID1`适合对数据安全性要求非常高的场景，比如存储数据库数据文件之类。

![RAID1][]

**实验**：`RAID1`创建，格式化，挂载使用，故障模拟，重新添加热备份。

1.添加`3`块`20G`的硬盘，分区，类型`ID`为`fd`。

2.创建`RAID1`，并添加`1`个热备份盘。

[root@localhost ~]# mdadm -C -v /dev/md1 -l1 -n2 /dev/sd{b,c}1 -x1 /dev/sdd1
    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: 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.

3.查看`raidstat`状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2](S) sdc1[1] sdb1[0]
          20953088 blocks super 1.2 [2/2] [UU]
          [========>............]  resync = 44.6% (9345792/20953088) finish=0.9min speed=203996K/sec
    
    unused devices: <none>

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2](S) sdc1[1] sdb1[0]
          20953088 blocks super 1.2 [2/2] [UU]
    
    unused devices: <none>

4.查看`RAID1`的详细信息。

[root@localhost ~]# mdadm -D /dev/md1
    /dev/md1:
               Version : 1.2
         Creation Time : Sun Aug 25 15:38:44 2019
            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 : Sun Aug 25 15:39:24 2019
                 State : clean, resyncing
        Active Devices : 2
       Working Devices : 3
        Failed Devices : 0
         Spare Devices : 1
    
    Consistency Policy : resync
    
         Resync Status : 40% complete
    
                  Name : localhost:1  (local to host localhost)
                  UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
                Events : 6
    
        Number   Major   Minor   RaidDevice State
           0       8       17        0      active sync   /dev/sdb1
           1       8       33        1      active sync   /dev/sdc1
    
           2       8       49        -      spare   /dev/sdd1

5.格式化。

[root@localhost ~]# mkfs.xfs /dev/md1
    meta-data=/dev/md1               isize=512    agcount=4, agsize=1309568 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0, sparse=0
    data     =                       bsize=4096   blocks=5238272, imaxpct=25
             =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
    log      =internal log           bsize=4096   blocks=2560, version=2
             =                       sectsz=512   sunit=0 blks, lazy-count=1
    realtime =none                   extsz=4096   blocks=0, rtextents=0

6.挂载使用。

[root@localhost ~]# mkdir /mnt/md1
    [root@localhost ~]# mount /dev/md1 /mnt/md1/
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G 1014M   16G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  904M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/md1                xfs        20G   33M   20G   1% /mnt/md1

7.创建测试文件。

[root@localhost ~]# touch /mnt/md1/test{1..9}.txt
    [root@localhost ~]# ls /mnt/md1/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

8.故障模拟。

[root@localhost ~]# mdadm -f /dev/md1 /dev/sdb1
    mdadm: set /dev/sdb1 faulty in /dev/md1

9.查看测试文件。

[root@localhost ~]# ls /mnt/md1/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

10.查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2] sdc1[1] sdb1[0](F)
          20953088 blocks super 1.2 [2/1] [_U]
          [=====>...............]  recovery = 26.7% (5600384/20953088) finish=1.2min speed=200013K/sec
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md1
    /dev/md1:
               Version : 1.2
         Creation Time : Sun Aug 25 15:38:44 2019
            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 : Sun Aug 25 15:47:57 2019
                 State : active, degraded, recovering
        Active Devices : 1
       Working Devices : 2
        Failed Devices : 1
         Spare Devices : 1
    
    Consistency Policy : resync
    
        Rebuild Status : 17% complete
    
                  Name : localhost:1  (local to host localhost)
                  UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
                Events : 22
    
        Number   Major   Minor   RaidDevice State
           2       8       49        0      spare rebuilding   /dev/sdd1
           1       8       33        1      active sync   /dev/sdc1
    
           0       8       17        -      faulty   /dev/sdb1

11.再次查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2] sdc1[1] sdb1[0](F)
          20953088 blocks super 1.2 [2/2] [UU]
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md1
    /dev/md1:
               Version : 1.2
         Creation Time : Sun Aug 25 15:38:44 2019
            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 : Sun Aug 25 15:49:28 2019
                 State : active
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 1
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:1  (local to host localhost)
                  UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
                Events : 37
    
        Number   Major   Minor   RaidDevice State
           2       8       49        0      active sync   /dev/sdd1
           1       8       33        1      active sync   /dev/sdc1
    
           0       8       17        -      faulty   /dev/sdb1

12.移除损坏的磁盘

[root@localhost ~]# mdadm -r /dev/md1 /dev/sdb1
    mdadm: hot removed /dev/sdb1 from /dev/md1

[root@localhost ~]# mdadm -D /dev/md1
    /dev/md1:
               Version : 1.2
         Creation Time : Sun Aug 25 15:38:44 2019
            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 : Sun Aug 25 15:52:57 2019
                 State : active
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:1  (local to host localhost)
                  UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
                Events : 38
    
        Number   Major   Minor   RaidDevice State
           2       8       49        0      active sync   /dev/sdd1
           1       8       33        1      active sync   /dev/sdc1

13.重新添加热备份盘。

[root@localhost ~]# mdadm -a /dev/md1 /dev/sdb1
    mdadm: added /dev/sdb1

[root@localhost ~]# mdadm -D /dev/md1
    /dev/md1:
               Version : 1.2
         Creation Time : Sun Aug 25 15:38:44 2019
            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 : Sun Aug 25 15:53:32 2019
                 State : active
        Active Devices : 2
       Working Devices : 3
        Failed Devices : 0
         Spare Devices : 1
    
    Consistency Policy : resync
    
                  Name : localhost:1  (local to host localhost)
                  UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
                Events : 39
    
        Number   Major   Minor   RaidDevice State
           2       8       49        0      active sync   /dev/sdd1
           1       8       33        1      active sync   /dev/sdc1
    
           3       8       17        -      spare   /dev/sdb1

--------------------

# RAID5 #

`RAID5`最少由三个硬盘组成，它将数据分散存储于阵列中的每个硬盘，并且还伴有一个数据校验位，数据位与校验位通过算法能相互验证，当丢失其中的一位时，`RAID`控制器能通过算法，利用其它两位数据将丢失的数据进行计算还原。因而`RAID5`最多能允许一个硬盘损坏，有容错性。`RAID5`相对于其它的组合方式，在容错与成本方面有一个平衡，因而受到大多数使用者的欢迎。一般的磁盘阵列，最常使用的就是`RAID5`这种方式。

![RAID5][]

**实验**：`RAID5`创建，格式化，挂载使用，故障模拟，重新添加热备份。

1.添加`4`块`20G`的硬盘，分区，类型`ID`为`fd`。

2.创建`RAID5`，并添加`1`个热备份盘。

[root@localhost ~]# mdadm -C -v /dev/md5 -l5 -n3 /dev/sd[b-d]1 -x1 /dev/sde1
    mdadm: layout defaults to left-symmetric
    mdadm: layout defaults to left-symmetric
    mdadm: chunk size defaults to 512K
    mdadm: size set to 20953088K
    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.

3.查看`raidstat`状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [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 [3/2] [UU_]
          [====>................]  recovery = 24.1% (5057340/20953088) finish=1.3min speed=202293K/sec
    
    unused devices: <none>

4.查看`RAID5`的详细信息。

[root@localhost ~]# mdadm -D /dev/md5
    /dev/md5:
               Version : 1.2
         Creation Time : Sun Aug 25 16:13:44 2019
            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 : Sun Aug 25 16:15:29 2019
                 State : clean
        Active Devices : 3
       Working Devices : 4
        Failed Devices : 0
         Spare Devices : 1
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:5  (local to host localhost)
                  UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
                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

5.格式化。

[root@localhost ~]# mkfs.xfs /dev/md5
    meta-data=/dev/md5               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

6.挂载使用。

[root@localhost ~]# mkdir /mnt/md5
    [root@localhost ~]# mount /dev/md5 /mnt/md5/
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G 1014M   16G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  904M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/md5                xfs        40G   33M   40G   1% /mnt/md5

7.创建测试文件。

[root@localhost ~]# touch /mnt/md5/test{1..9}.txt
    [root@localhost ~]# ls /mnt/md5/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

8.故障模拟。

[root@localhost ~]# mdadm -f /dev/md5 /dev/sdb1
    mdadm: set /dev/sdb1 faulty in /dev/md5

9.查看测试文件。

[root@localhost ~]# ls /mnt/md5/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

10.查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid6] [raid5] [raid4]
    md5 : active raid5 sdd1[4] sde1[3] sdc1[1] sdb1[0](F)
          41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
          [====>................]  recovery = 21.0% (4411136/20953088) finish=1.3min speed=210054K/sec
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md5
    /dev/md5:
               Version : 1.2
         Creation Time : Sun Aug 25 16:13:44 2019
            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 : Sun Aug 25 16:21:31 2019
                 State : clean, degraded, recovering
        Active Devices : 2
       Working Devices : 3
        Failed Devices : 1
         Spare Devices : 1
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
        Rebuild Status : 12% complete
    
                  Name : localhost:5  (local to host localhost)
                  UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
                Events : 23
    
        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

11.再次查看状态。

[root@localhost ~]# mdadm -D /dev/md5
    /dev/md5:
               Version : 1.2
         Creation Time : Sun Aug 25 16:13:44 2019
            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 : Sun Aug 25 16:23:09 2019
                 State : clean
        Active Devices : 3
       Working Devices : 3
        Failed Devices : 1
         Spare Devices : 0
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:5  (local to host localhost)
                  UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
                Events : 39
    
        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

12.移除损坏的磁盘。

[root@localhost ~]# mdadm -r /dev/md5 /dev/sdb1
    mdadm: hot removed /dev/sdb1 from /dev/md5

[root@localhost ~]# mdadm -D /dev/md5
    /dev/md5:
               Version : 1.2
         Creation Time : Sun Aug 25 16:13:44 2019
            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 : 3
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:25:01 2019
                 State : clean
        Active Devices : 3
       Working Devices : 3
        Failed Devices : 0
         Spare Devices : 0
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:5  (local to host localhost)
                  UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
                Events : 40
    
        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

13.重新添加热备份盘。

[root@localhost ~]# mdadm -a /dev/md5 /dev/sdb1
    mdadm: added /dev/sdb1

[root@localhost ~]# mdadm -D /dev/md5
    /dev/md5:
               Version : 1.2
         Creation Time : Sun Aug 25 16:13:44 2019
            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 : Sun Aug 25 16:25:22 2019
                 State : clean
        Active Devices : 3
       Working Devices : 4
        Failed Devices : 0
         Spare Devices : 1
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:5  (local to host localhost)
                  UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
                Events : 41
    
        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
    
           5       8       17        -      spare   /dev/sdb1

--------------------

# RAID6 #

`RAID6`是在`RAID5`的基础上改良而成的，`RAID6`再将数据校验位增加一位，所以允许损坏的硬盘数量也由 `RAID5`的一个增加到二个。由于同一阵列中两个硬盘同时损坏的概率非常少，所以，`RAID6`用增加一块硬盘的代价，换来了比`RAID5`更高的数据安全性。

![RAID6][]

**实验**：`RAID6`创建，格式化，挂载使用，故障模拟，重新添加热备份。

1.添加`6`块`20G`的硬盘，分区，类型`ID`为`fd`。

[root@localhost ~]# fdisk -l | grep raid
    /dev/sdb1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sdc1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sdd1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sde1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sdf1            2048    41943039    20970496   fd  Linux raid autodetect
    /dev/sdg1            2048    41943039    20970496   fd  Linux raid autodetect

2.创建`RAID6`，并添加`2`个热备份盘。

[root@localhost ~]# mdadm -C -v /dev/md6 -l6 -n4 /dev/sd[b-e]1 -x2 /dev/sd[f-g]1
    mdadm: layout defaults to left-symmetric
    mdadm: layout defaults to left-symmetric
    mdadm: chunk size defaults to 512K
    mdadm: size set to 20953088K
    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.

3.查看`raidstat`状态。

[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]
          41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
          [===>.................]  resync = 18.9% (3962940/20953088) finish=1.3min speed=208575K/sec
    
    unused devices: <none>

4.查看`RAID6`的详细信息。

[root@localhost ~]# mdadm -D /dev/md6
    /dev/md6:
               Version : 1.2
         Creation Time : Sun Aug 25 16:34:36 2019
            Raid Level : raid6
            Array Size : 41906176 (39.96 GiB 42.91 GB)
         Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
          Raid Devices : 4
         Total Devices : 6
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:34:43 2019
                 State : clean, resyncing
        Active Devices : 4
       Working Devices : 6
        Failed Devices : 0
         Spare Devices : 2
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
         Resync Status : 10% complete
    
                  Name : localhost:6  (local to host localhost)
                  UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
                Events : 1
    
        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

5.格式化。

[root@localhost ~]# mkfs.xfs /dev/md6
    meta-data=/dev/md6               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

6.挂载使用。

[root@localhost ~]# mkdir /mnt/md6
    [root@localhost ~]# mount /dev/md6 /mnt/md6/
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G 1014M   16G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  903M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/md6                xfs        40G   33M   40G   1% /mnt/md6

7.创建测试文件。

[root@localhost ~]# touch /mnt/md6/test{1..9}.txt
    [root@localhost ~]# ls /mnt/md6/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

8.故障模拟。

[root@localhost ~]# mdadm -f /dev/md6 /dev/sdb1
    mdadm: set /dev/sdb1 faulty in /dev/md6
    [root@localhost ~]# mdadm -f /dev/md6 /dev/sdc1
    mdadm: set /dev/sdc1 faulty in /dev/md6

9.查看测试文件。

[root@localhost ~]# ls /mnt/md6/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

10.查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid6] [raid5] [raid4]
    md6 : active raid6 sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1](F) sdb1[0](F)
          41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/2] [__UU]
          [====>................]  recovery = 23.8% (4993596/20953088) finish=1.2min speed=208066K/sec
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md6
    /dev/md6:
               Version : 1.2
         Creation Time : Sun Aug 25 16:34:36 2019
            Raid Level : raid6
            Array Size : 41906176 (39.96 GiB 42.91 GB)
         Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
          Raid Devices : 4
         Total Devices : 6
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:41:09 2019
                 State : clean, degraded, recovering
        Active Devices : 2
       Working Devices : 4
        Failed Devices : 2
         Spare Devices : 2
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
        Rebuild Status : 13% complete
    
                  Name : localhost:6  (local to host localhost)
                  UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
                Events : 27
    
        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

11.再次查看状态。

[root@localhost ~]# mdadm -D /dev/md6
    /dev/md6:
               Version : 1.2
         Creation Time : Sun Aug 25 16:34:36 2019
            Raid Level : raid6
            Array Size : 41906176 (39.96 GiB 42.91 GB)
         Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
          Raid Devices : 4
         Total Devices : 6
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:42:42 2019
                 State : clean
        Active Devices : 4
       Working Devices : 4
        Failed Devices : 2
         Spare Devices : 0
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:6  (local to host localhost)
                  UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
                Events : 46
    
        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

12.移除损坏的磁盘。

[root@localhost ~]# mdadm -r /dev/md6 /dev/sd{b,c}1
    mdadm: hot removed /dev/sdb1 from /dev/md6
    mdadm: hot removed /dev/sdc1 from /dev/md6

[root@localhost ~]# mdadm -D /dev/md6
    /dev/md6:
               Version : 1.2
         Creation Time : Sun Aug 25 16:34:36 2019
            Raid Level : raid6
            Array Size : 41906176 (39.96 GiB 42.91 GB)
         Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
          Raid Devices : 4
         Total Devices : 4
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:43:43 2019
                 State : clean
        Active Devices : 4
       Working Devices : 4
        Failed Devices : 0
         Spare Devices : 0
    
                Layout : left-symmetric
            Chunk Size : 512K
    
    Consistency Policy : resync
    
                  Name : localhost:6  (local to host localhost)
                  UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
                Events : 47
    
        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

13.重新添加热备份盘。

[root@localhost ~]# mdadm -a /dev/md6 /dev/sd{b,c}1
    mdadm: added /dev/sdb1
    mdadm: added /dev/sdc1

[root@localhost ~]# mdadm -D /dev/md6
    /dev/md6:
               Version : 1.2
         Creation Time : Sun Aug 25 16:34:36 2019
            Raid Level : raid6
            Array Size : 41906176 (39.96 GiB 42.91 GB)
         Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
          Raid Devices : 4
         Total Devices : 6
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:44:01 2019
                 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:6  (local to host localhost)
                  UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
                Events : 49
    
        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
    
           6       8       17        -      spare   /dev/sdb1
           7       8       33        -      spare   /dev/sdc1

--------------------

# RAID10 #

`RAID10`是先将数据进行镜像操作，然后再对数据进行分组，`RAID1`在这里就是一个冗余的备份阵列，而`RAID0`则负责数据的读写阵列。至少要四块盘，两两组合做`RAID1`，然后做`RAID0`，`RAID10`对存储容量的利用率和`RAID1`一样低，只有`50%`。`Raid10`方案造成了`50%`的磁盘浪费，但是它提供了`200%`的速度和单磁盘损坏的数据安全性，并且当同时损坏的磁盘不在同一`RAID1`中，就能保证数据安全性，`RAID10`能提供比`RAID5`更好的性能。这种新结构的可扩充性不好，使用此方案比较昂贵。

![RAID10][]

**实验**：`RAID10`创建，格式化，挂载使用，故障模拟，重新添加热备份。

1.添加`4`块`20G`的硬盘，分区，类型`ID`为`fd`。

2.创建两个`RAID1`，不添加热备份盘。

[root@localhost ~]# mdadm -C -v /dev/md101 -l1 -n2 /dev/sd{b,c}1
    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: size set to 20953088K
    Continue creating array? y
    mdadm: Fail create md101 when using /sys/module/md_mod/parameters/new_array
    mdadm: Defaulting to version 1.2 metadata
    mdadm: array /dev/md101 started.

[root@localhost ~]# mdadm -C -v /dev/md102 -l1 -n2 /dev/sd{d,e}1
    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: size set to 20953088K
    Continue creating array? y
    mdadm: Fail create md102 when using /sys/module/md_mod/parameters/new_array
    mdadm: Defaulting to version 1.2 metadata
    mdadm: array /dev/md102 started.

3.查看`raidstat`状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md102 : active raid1 sde1[1] sdd1[0]
          20953088 blocks super 1.2 [2/2] [UU]
          [=========>...........]  resync = 48.4% (10148224/20953088) finish=0.8min speed=200056K/sec
    
    md101 : active raid1 sdc1[1] sdb1[0]
          20953088 blocks super 1.2 [2/2] [UU]
          [=============>.......]  resync = 69.6% (14604672/20953088) finish=0.5min speed=200052K/sec
    
    unused devices: <none>

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1]
    md102 : active raid1 sde1[1] sdd1[0]
          20953088 blocks super 1.2 [2/2] [UU]
    
    md101 : active raid1 sdc1[1] sdb1[0]
          20953088 blocks super 1.2 [2/2] [UU]
    
    unused devices: <none>

4.查看两个`RAID1`的详细信息。

[root@localhost ~]# mdadm -D /dev/md101
    /dev/md101:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:00 2019
            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 : Sun Aug 25 16:53:58 2019
                 State : clean, resyncing
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
         Resync Status : 62% complete
    
                  Name : localhost:101  (local to host localhost)
                  UUID : 80bb4fc5:1a628936:275ba828:17f23330
                Events : 9
    
        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/md102
    /dev/md102:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:23 2019
            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 : Sun Aug 25 16:54:02 2019
                 State : clean, resyncing
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
         Resync Status : 42% complete
    
                  Name : localhost:102  (local to host localhost)
                  UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
                Events : 6
    
        Number   Major   Minor   RaidDevice State
           0       8       49        0      active sync   /dev/sdd1
           1       8       65        1      active sync   /dev/sde1

5.创建`RAID10`。

[root@localhost ~]# mdadm -C -v /dev/md10 -l0 -n2 /dev/md10{1,2}
    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.

6.查看`raidstat`状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1] [raid0]
    md10 : active raid0 md102[1] md101[0]
          41871360 blocks super 1.2 512k chunks
    
    md102 : active raid1 sde1[1] sdd1[0]
          20953088 blocks super 1.2 [2/2] [UU]
    
    md101 : active raid1 sdc1[1] sdb1[0]
          20953088 blocks super 1.2 [2/2] [UU]
    
    unused devices: <none>

7.查看`RAID10`的详细信息。

[root@localhost ~]# mdadm -D /dev/md10
    /dev/md10:
               Version : 1.2
         Creation Time : Sun Aug 25 16:56:08 2019
            Raid Level : raid0
            Array Size : 41871360 (39.93 GiB 42.88 GB)
          Raid Devices : 2
         Total Devices : 2
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 16:56:08 2019
                 State : clean
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
            Chunk Size : 512K
    
    Consistency Policy : none
    
                  Name : localhost:10  (local to host localhost)
                  UUID : 23c6abac:b131a049:db25cac8:686fb045
                Events : 0
    
        Number   Major   Minor   RaidDevice State
           0       9      101        0      active sync   /dev/md101
           1       9      102        1      active sync   /dev/md102

8.格式化。

[root@localhost ~]# mkfs.xfs /dev/md10
    meta-data=/dev/md10              isize=512    agcount=16, agsize=654208 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0, sparse=0
    data     =                       bsize=4096   blocks=10467328, imaxpct=25
             =                       sunit=128    swidth=256 blks
    naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
    log      =internal log           bsize=4096   blocks=5112, version=2
             =                       sectsz=512   sunit=8 blks, lazy-count=1
    realtime =none                   extsz=4096   blocks=0, rtextents=0

9.挂载使用。

[root@localhost ~]# mkdir /mnt/md10
    [root@localhost ~]# mount /dev/md10 /mnt/md10/
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G 1014M   16G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  903M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/md10               xfs        40G   33M   40G   1% /mnt/md10

10.创建测试文件。

[root@localhost ~]# touch /mnt/md10/test{1..9}.txt
    [root@localhost ~]# ls /mnt/md10/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

11.故障模拟。

[root@localhost ~]# mdadm -f /dev/md101 /dev/sdb1
    mdadm: set /dev/sdb1 faulty in /dev/md101
    [root@localhost ~]# mdadm -f /dev/md102 /dev/sdd1
    mdadm: set /dev/sdd1 faulty in /dev/md102

12.查看测试文件。

[root@localhost ~]# ls /mnt/md10/
    test1.txt  test2.txt  test3.txt  test4.txt  test5.txt  test6.txt  test7.txt  test8.txt  test9.txt

13.查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1] [raid0]
    md10 : active raid0 md102[1] md101[0]
          41871360 blocks super 1.2 512k chunks
    
    md102 : active raid1 sde1[1] sdd1[0](F)
          20953088 blocks super 1.2 [2/1] [_U]
    
    md101 : active raid1 sdc1[1] sdb1[0](F)
          20953088 blocks super 1.2 [2/1] [_U]
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md101
    /dev/md101:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:00 2019
            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 : Sun Aug 25 17:01:11 2019
                 State : clean, degraded
        Active Devices : 1
       Working Devices : 1
        Failed Devices : 1
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:101  (local to host localhost)
                  UUID : 80bb4fc5:1a628936:275ba828:17f23330
                Events : 23
    
        Number   Major   Minor   RaidDevice State
           -       0        0        0      removed
           1       8       33        1      active sync   /dev/sdc1
    
           0       8       17        -      faulty   /dev/sdb1

[root@localhost ~]# mdadm -D /dev/md102
    /dev/md102:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:23 2019
            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 : Sun Aug 25 17:00:43 2019
                 State : clean, degraded
        Active Devices : 1
       Working Devices : 1
        Failed Devices : 1
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:102  (local to host localhost)
                  UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
                Events : 19
    
        Number   Major   Minor   RaidDevice State
           -       0        0        0      removed
           1       8       65        1      active sync   /dev/sde1
    
           0       8       49        -      faulty   /dev/sdd1

14.移除损坏的磁盘。

[root@localhost ~]# mdadm -r /dev/md101 /dev/sdb1
    mdadm: hot removed /dev/sdb1 from /dev/md101
    [root@localhost ~]# mdadm -r /dev/md102 /dev/sdd1
    mdadm: hot removed /dev/sdd1 from /dev/md102

[root@localhost ~]# mdadm -D /dev/md101
    /dev/md101:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:00 2019
            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 : 1
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 17:04:59 2019
                 State : clean, degraded
        Active Devices : 1
       Working Devices : 1
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:101  (local to host localhost)
                  UUID : 80bb4fc5:1a628936:275ba828:17f23330
                Events : 26
    
        Number   Major   Minor   RaidDevice State
           -       0        0        0      removed
           1       8       33        1      active sync   /dev/sdc1

[root@localhost ~]# mdadm -D /dev/md102
    /dev/md102:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:23 2019
            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 : 1
           Persistence : Superblock is persistent
    
           Update Time : Sun Aug 25 17:05:07 2019
                 State : clean, degraded
        Active Devices : 1
       Working Devices : 1
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:102  (local to host localhost)
                  UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
                Events : 20
    
        Number   Major   Minor   RaidDevice State
           -       0        0        0      removed
           1       8       65        1      active sync   /dev/sde1

15.重新添加热备份盘。

[root@localhost ~]# mdadm -a /dev/md101 /dev/sdb1
    mdadm: added /dev/sdb1
    [root@localhost ~]# mdadm -a /dev/md102 /dev/sdd1
    mdadm: added /dev/sdd1

16.再次查看状态。

[root@localhost ~]# cat /proc/mdstat
    Personalities : [raid1] [raid0]
    md10 : active raid0 md102[1] md101[0]
          41871360 blocks super 1.2 512k chunks
    
    md102 : active raid1 sdd1[2] sde1[1]
          20953088 blocks super 1.2 [2/1] [_U]
          [====>................]  recovery = 23.8% (5000704/20953088) finish=1.2min speed=208362K/sec
    
    md101 : active raid1 sdb1[2] sdc1[1]
          20953088 blocks super 1.2 [2/1] [_U]
          [======>..............]  recovery = 32.0% (6712448/20953088) finish=1.1min speed=203407K/sec
    
    unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md101
    /dev/md101:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:00 2019
            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 : Sun Aug 25 17:07:28 2019
                 State : clean
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:101  (local to host localhost)
                  UUID : 80bb4fc5:1a628936:275ba828:17f23330
                Events : 45
    
        Number   Major   Minor   RaidDevice State
           2       8       17        0      active sync   /dev/sdb1
           1       8       33        1      active sync   /dev/sdc1

[root@localhost ~]# mdadm -D /dev/md102
    /dev/md102:
               Version : 1.2
         Creation Time : Sun Aug 25 16:53:23 2019
            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 : Sun Aug 25 17:07:36 2019
                 State : clean
        Active Devices : 2
       Working Devices : 2
        Failed Devices : 0
         Spare Devices : 0
    
    Consistency Policy : resync
    
                  Name : localhost:102  (local to host localhost)
                  UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
                Events : 39
    
        Number   Major   Minor   RaidDevice State
           2       8       49        0      active sync   /dev/sdd1
           1       8       65        1      active sync   /dev/sde1

--------------------

# 常用 RAID 间比较 #

<table> 
 <thead> 
  <tr> 
   <th style="text-align:left;">名称</th> 
   <th style="text-align:center;">硬盘数量</th> 
   <th style="text-align:center;">容量/利用率</th> 
   <th style="text-align:center;">读性能</th> 
   <th style="text-align:center;">写性能</th> 
   <th style="text-align:left;">数据冗余</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td style="text-align:left;">RAID0</td> 
   <td style="text-align:center;">N</td> 
   <td style="text-align:center;">N块总和</td> 
   <td style="text-align:center;">N倍</td> 
   <td style="text-align:center;">N倍</td> 
   <td style="text-align:left;">无，一个故障，丢失所有数据</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">RAID1</td> 
   <td style="text-align:center;">N（偶数）</td> 
   <td style="text-align:center;">50%</td> 
   <td style="text-align:center;">↑</td> 
   <td style="text-align:center;">↓</td> 
   <td style="text-align:left;">写两个设备，允许一个故障</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">RAID5</td> 
   <td style="text-align:center;">N≥3</td> 
   <td style="text-align:center;">(N-1)/N</td> 
   <td style="text-align:center;">↑↑</td> 
   <td style="text-align:center;">↓</td> 
   <td style="text-align:left;">计算校验，允许一个故障</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">RAID6</td> 
   <td style="text-align:center;">N≥4</td> 
   <td style="text-align:center;">(N-2)/N</td> 
   <td style="text-align:center;">↑↑</td> 
   <td style="text-align:center;">↓↓</td> 
   <td style="text-align:left;">双重校验，允许两个故障</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">RAID10</td> 
   <td style="text-align:center;">N（偶数，N≥4）</td> 
   <td style="text-align:center;">50%</td> 
   <td style="text-align:center;">(N/2)倍</td> 
   <td style="text-align:center;">(N/2)倍</td> 
   <td style="text-align:left;">允许基组中的磁盘各损坏一个</td> 
  </tr> 
 </tbody> 
</table>

--------------------

# 一些话 #

此篇涉及到的操作很简单，但是，有很多的查看占用了大量的篇幅，看关键点，过程都是一个套路，都是重复的。

转载于:https://www.cnblogs.com/llife/p/11408941.html

[CentOS-Logo]: /images/20230601/8321681709c04ffe96fcb08f8f34f670.png
[RAID0]: /images/20230601/c5e4082a9edc4753aad047d1290fd874.png
[RAID1]: /images/20230601/c666a77f658a4d61af79e26fe84b3804.png
[RAID5]: /images/20230601/5c20ca00f4b2432aaf58b4c23b7e7f82.png
[RAID6]: /images/20230601/976ad187742943cda626666186df6550.png
[RAID10]: /images/20230601/afafd7b489fb41e2952f058a52f14beb.png