$ sudo mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Sat Jan 9 16:36:18 2021 Raid Level : raid1 Array Size : 2094080 (2045.00 MiB 2144.34 MB) Used Dev Size : 2094080 (2045.00 MiB 2144.34 MB) Raid Devices : 3 Total Devices : 3 Persistence : Superblock is persistent Update Time : Sat Jan 9 16:36:21 2021 State : clean, resyncing Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Consistency Policy : resync Resync Status : 23% complete Name : dev-machine:0 (local to host dev-machine) UUID : e0e5d514:d2294825:45d9f09c:db485a0c Events : 3 Number Major Minor RaidDevice State 0 252 0 0 active sync /dev/rd0 1 8 34 1 active sync writemostly /dev/sdc2 2 8 50 2 active sync writemostly /dev/sdd2