mdadm --detail /dev/md2

        Version : 0.90
  Creation Time : Mon Jun  4 01:46:39 2018
     Raid Level : raid1
     Array Size : 20478912 (19.53 GiB 20.97 GB)
  Used Dev Size : 20478912 (19.53 GiB 20.97 GB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Wed Sep 25 11:17:01 2019
          State : active
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

           UUID : 87f62257:1b1d7de1:a4d2adc2:26fd5302
         Events : 0.498

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2
       2       8       34        2      active sync   /dev/sdc2