给 RAID5 添加热备盘

创建 RAID5 时设置 1 块热备盘；

[root@zhpj ~]# mdadm -Cv /dev/md5 -n 3 -l 5 -x 1 /dev/sd{b..e}
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: size set to 10476544K
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.
[root@zhpj ~]# 
[root@zhpj ~]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] 
md5 : active raid5 sdd[4] sde[3](S) sdc[1] sdb[0]
      20953088 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [UU_]
      [=>...................]  recovery =  9.4% (990556/10476544) finish=0.6min speed=247639K/sec
    
unused devices: <none>
[root@zhpj ~]#


[root@zhpj ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Sun Aug 11 20:43:45 2024
        Raid Level : raid5
        Array Size : 20953088 (19.98 GiB 21.46 GB)
     Used Dev Size : 10476544 (9.99 GiB 10.73 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent

       Update Time : Sun Aug 11 20:44:24 2024
             State : clean, degraded, recovering 
    Active Devices : 2
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 2

            Layout : left-symmetric
        Chunk Size : 512K

Consistency Policy : resync

    Rebuild Status : 78% complete

              Name : zhpj.com:5  (local to host zhpj.com)
              UUID : 67b6c832:892ea5d8:975505f9:528f99e0
            Events : 13

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       4       8       48        2      spare rebuilding   /dev/sdd

       3       8       64        -      spare   /dev/sde
[root@zhpj ~]# 

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​/dev/sdb​ 模拟为故障，热备盘 /dev/sde​ 会自动替换上去；

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RAID5允许坏一块磁盘，热备盘替换上去之后，还允许再坏一块磁盘：

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移除两块坏掉的硬盘：

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向 RAID5 添加磁盘：

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向 RAID5 添加热备盘：

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