mdadm --detail /dev/md1

        Version : 0.90
  Creation Time : Mon Jun  4 01:46:39 2018
     Raid Level : raid1
     Array Size : 523200 (510.94 MiB 535.76 MB)
  Used Dev Size : 523200 (510.94 MiB 535.76 MB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Tue Sep 24 23:29:08 2019
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

           UUID : 6bd1ac89:cdfc2850:a4d2adc2:26fd5302
         Events : 0.46

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1