root@omv30:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md0 : active (auto-read-only) raid1 sdb[0] sdc[1]
      1047552 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>
root@omv30:~# fdisk -l
...（省略）

Disk /dev/md0: 1023 MiB, 1072693248 bytes, 2095104 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

mount后访问正常。

2、更换硬盘位置测试

关机，新增一块硬盘，占用原来sdc的位置，启动：

root@omv30:~# mdadm -D /dev/md0 
/dev/md0:
        Version : 1.2
  Creation Time : Sun Sep 30 22:31:39 2018
     Raid Level : raid1
     Array Size : 1047552 (1023.00 MiB 1072.69 MB)
  Used Dev Size : 1047552 (1023.00 MiB 1072.69 MB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Mon Oct  1 19:52:46 2018
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : omv30:raid1  (local to host omv30)
           UUID : 921a8946:b273e00e:3fa4b99d:040a4437
         Events : 29

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       48        1      active sync   /dev/sdd

root@omv30:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md0 : active (auto-read-only) raid1 sdb[0] sdd[1]
      1047552 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

原来的sdc变成了sdc，raid1还完好保存，不受影响。

3、移除硬盘测试

关机，然后移除一块硬盘，启动：

root@omv30:~# mdadm -D /dev/md0 
/dev/md0:
        Version : 1.2
     Raid Level : raid0
  Total Devices : 1
    Persistence : Superblock is persistent

          State : inactive

           Name : omv30:raid1  (local to host omv30)
           UUID : 921a8946:b273e00e:3fa4b99d:040a4437
         Events : 29

    Number   Major   Minor   RaidDevice

       -       8       16        -        /dev/sdb

root@omv30:~# mdadm --query /dev/sdb
/dev/sdb: is not an md array
/dev/sdb: device 0 in 2 device undetected raid1 /dev/md0.  Use mdadm --examine for more detail.

root@omv30:~# mdadm --examine /dev/sdb
/dev/sdb:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 921a8946:b273e00e:3fa4b99d:040a4437
           Name : omv30:raid1  (local to host omv30)
  Creation Time : Sun Sep 30 22:31:39 2018
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 2095104 (1023.00 MiB 1072.69 MB)
     Array Size : 1047552 (1023.00 MiB 1072.69 MB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1960 sectors, after=0 sectors
          State : clean
    Device UUID : 6e545465:3dcf10df:1d5bb938:fe840307

    Update Time : Mon Oct  1 19:52:46 2018
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : a47a7d1f - correct
         Events : 29


   Device Role : Active device 0
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)