软 RAID

mdadm 命令

创建软 raid
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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
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mdadm -D /dev/设备名
查看 RAID 状态
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cat /proc/mdstat
模拟损坏
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mdadm -f /dev/设备名磁盘
移除损坏的磁盘
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mdadm -r /dev/设备名磁盘
添加新硬盘作为热备份盘
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mdadm -a /dev/设备名磁盘

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
实验: RAID0创建，格式化，挂载使用

添加2块20G的硬盘，分区，类型ID为fd

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

创建RAID0

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[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.

查看raidstat状态

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[root@localhost ~]# cat /proc/mdstat
Personalities : [raid0]
md0 : active raid0 sdc1[1] sdb1[0]
      41906176 blocks super 1.2 512k chunks

unused devices: <none>

查看RAID0的详细信息

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[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

格式化

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[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

挂载使用

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[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
实验: RAID1创建，格式化，挂载使用，故障模拟，重新添加热备份

添加3块20G的硬盘，分区，类型ID为fd。

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[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

创建RAID1，并添加1个热备份盘。

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[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.

查看raidstat状态。

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[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>

查看RAID1的详细信息。

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[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

格式化。

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[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

挂载使用。

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[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

创建测试文件。

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[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

故障模拟。

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

查看测试文件。

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

查看状态。

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[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

再次查看状态

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[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

移除损坏的磁盘

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[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

重新添加热备份盘。

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[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
实验: RAID5创建，格式化，挂载使用，故障模拟，重新添加热备份

添加4块20G的硬盘，分区，类型ID为fd。

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[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

创建RAID5，并添加1个热备份盘。

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[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.

查看raidstat状态。

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[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>

[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 [3/3] [UUU]

unused devices: <none>

查看RAID5的详细信息。

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[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

格式化。

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[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

挂载使用。

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[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

创建测试文件。

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[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

故障模拟。

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

查看测试文件。

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

查看状态。

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[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

再次查看状态。

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[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 [3/3] [UUU]

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 16:23:09 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

移除损坏的磁盘。

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[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

重新添加热备份盘。

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[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
实验: RAID6创建，格式化，挂载使用，故障模拟，重新添加热备份

添加6块20G的硬盘，分区，类型ID为fd。

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[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

创建RAID6，并添加2个热备份盘。

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[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.

查看raidstat状态。

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[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>

[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]

unused devices: <none>

查看RAID6的详细信息。

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[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

格式化。

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[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

挂载使用。

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[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

创建测试文件。

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[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

故障模拟。

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[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

查看测试文件。

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

查看状态。

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[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

再次查看状态。

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[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 [4/4] [UUUU]

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 16:42:42 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

移除损坏的磁盘。

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[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

重新添加热备份盘。

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[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
实验: RAID10创建，格式化，挂载使用，故障模拟，重新添加热备份

添加4块20G的硬盘，分区，类型ID为fd。

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[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

创建两个RAID1，不添加热备份盘。

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[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.

查看raidstat状态。

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[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>

查看两个RAID1的详细信息。

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[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

创建RAID10。

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[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.

查看raidstat状态。

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[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>

查看RAID10的详细信息。

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[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

格式化。

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[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

挂载使用。

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[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

创建测试文件。

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[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

故障模拟。

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[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

查看测试文件。

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

查看状态。

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[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

[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

移除损坏的磁盘。

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[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

重新添加热备份盘。

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

再次查看状态。

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[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 ~]# 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 [2/2] [UU]

md101 : active raid1 sdb1[2] sdc1[1]
      20953088 blocks super 1.2 [2/2] [UU]

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 比较

名称	硬盘数量	容量/利用率	读性能	写性能	数据冗余
RAID0	N	N块总和	N倍	N倍	无，一个故障，丢失所有数据
RAID1	N(偶数)	50%	↑	↓	写两个设备，允许一个故障
RAID5	N≥3	(N-1)/N	↑↑	↓	计算校验，允许一个故障
RAID6	N≥4	(N-2)/N	↑↑	↓↓	双重校验，允许两个故障
RAID10	N(偶数，N≥4)	50%	(N/2)倍	(N/2)倍	允许基组中的磁盘各损坏一个

参考

https://www.linuxidc.com/Linux/2019-08/160345.htm

文章目录

mdadm 命令

RAID0

RAID1

RAID5

RAID6

RAID10

常用 RAID 比较

参考