centos raid 软阵列的使用

创建一个 raid 设备

[root@localhost /]# mknod /dev/md1 b 9 1

• mknod 是命令
• /dev/md1 是设备名称，设备名称必须是 md开头后面的 b 代表的是块设备
• 9 是主设备号 ，1是从设备号
• 主设备号不能更改，从设备号系统唯一

创建 raid 5

[root@localhost /]# mdadm -C /dev/md1 -l 5 -n 3 /dev/sdc5 /dev/sdc6 /dev/sdc7
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.

-C代表创建，指定块设备的路径
-l 指定 raid 级别为5
-n 代表硬盘数量

查看

[root@localhost /]# mdadm --detail /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Sat Apr 22 14:55:36 2017
     Raid Level : raid5
     Array Size : 1021952 (998.00 MiB 1046.48 MB)
  Used Dev Size : 510976 (499.00 MiB 523.24 MB)
   Raid Devices : 3
  Total Devices : 3
    Persistence : Superblock is persistent

    Update Time : Sat Apr 22 14:55:39 2017
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : localhost.localdomain:1  (local to host localhost.localdomain)
           UUID : 2a5294bf:dd845f28:c6c3fa2e:ed6d5d20
         Events : 18

    Number   Major   Minor   RaidDevice State
       0       8       37        0      active sync   /dev/sdc5
       1       8       38        1      active sync   /dev/sdc6
       3       8       39        2      active sync   /dev/sdc7

格式化挂载

[root@localhost /]# mkfs -t xfs /dev/md1
meta-data=/dev/md1               isize=512    agcount=8, agsize=31872 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=254976, imaxpct=25
         =                       sunit=128    swidth=256 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=624, version=2
         =                       sectsz=512   sunit=8 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
[root@localhost /]# mount /dev/md1 /mnt/data

模拟失效

[root@localhost data]# mdadm  /dev/md1 -f /dev/sdc7
mdadm: set /dev/sdc7 faulty in /dev/md1

查看

[root@localhost data]# mdadm --detail /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Sat Apr 22 14:55:36 2017
     Raid Level : raid5
     Array Size : 1021952 (998.00 MiB 1046.48 MB)
  Used Dev Size : 510976 (499.00 MiB 523.24 MB)
   Raid Devices : 3
  Total Devices : 3
    Persistence : Superblock is persistent

    Update Time : Sat Apr 22 15:04:02 2017
          State : clean, degraded
 Active Devices : 2
Working Devices : 2
 Failed Devices : 1
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : localhost.localdomain:1  (local to host localhost.localdomain)
           UUID : 2a5294bf:dd845f28:c6c3fa2e:ed6d5d20
         Events : 22

    Number   Major   Minor   RaidDevice State
       0       8       37        0      active sync   /dev/sdc5
       1       8       38        1      active sync   /dev/sdc6
       -       0        0        2      removed

       3       8       39        -      faulty   /dev/sdc7

移除

[root@localhost data]# mdadm /dev/md1 --remove /dev/sdc7
mdadm: hot removed /dev/sdc7 from /dev/md1
[root@localhost data]# mdadm --detail /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Sat Apr 22 14:55:36 2017
     Raid Level : raid5
     Array Size : 1021952 (998.00 MiB 1046.48 MB)
  Used Dev Size : 510976 (499.00 MiB 523.24 MB)
   Raid Devices : 3
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Sat Apr 22 15:05:02 2017
          State : clean, degraded
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : localhost.localdomain:1  (local to host localhost.localdomain)
           UUID : 2a5294bf:dd845f28:c6c3fa2e:ed6d5d20
         Events : 27

    Number   Major   Minor   RaidDevice State
       0       8       37        0      active sync   /dev/sdc5
       1       8       38        1      active sync   /dev/sdc6
       -       0        0        2      removed

添加

[root@localhost data]# mdadm /dev/md1 --add /dev/sdc7
mdadm: added /dev/sdc7
[root@localhost data]# mdadm --detail /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Sat Apr 22 14:55:36 2017
     Raid Level : raid5
     Array Size : 1021952 (998.00 MiB 1046.48 MB)
  Used Dev Size : 510976 (499.00 MiB 523.24 MB)
   Raid Devices : 3
  Total Devices : 3
    Persistence : Superblock is persistent

    Update Time : Sat Apr 22 15:05:52 2017
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : localhost.localdomain:1  (local to host localhost.localdomain)
           UUID : 2a5294bf:dd845f28:c6c3fa2e:ed6d5d20
         Events : 46

    Number   Major   Minor   RaidDevice State
       0       8       37        0      active sync   /dev/sdc5
       1       8       38        1      active sync   /dev/sdc6
       3       8       39        2      active sync   /dev/sdc7