Determine software RAID array (Multiple Device driver aka Linux Software RAID) state using command-line utility.
First case
Determine MD array status.
$ sudo mdadm --detail /dev/md0
/dev/md0: Version : 1.2 Creation Time : Tue May 24 17:50:17 2022 Raid Level : raid1 Array Size : 960806720 (916.30 GiB 983.87 GB) Used Dev Size : 960806720 (916.30 GiB 983.87 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Intent Bitmap : Internal Update Time : Sun May 29 22:45:38 2022 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Consistency Policy : bitmap Name : pxe-rescue:0 UUID : bfdfd734:8476c2c5:160c8d7e:336308bf Events : 4749 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 1 8 18 1 active sync /dev/sdb2
Determine MD array status using exit code.
$ sudo mdadm --detail --test /dev/md0 1>/dev/null
$ echo $?
0
Exit code `` means that array is functioning normally.
Second case
Determine MD array status.
$ sudo mdadm --detail /dev/md1
/dev/md1: Version : 1.2 Creation Time : Tue May 24 17:50:17 2022 Raid Level : raid1 Array Size : 15813504 (15.08 GiB 16.19 GB) Used Dev Size : 15813504 (15.08 GiB 16.19 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Sun May 29 22:39:54 2022 State : clean, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Consistency Policy : resync Name : pxe-rescue:1 UUID : 5d9ec27a:bfb45b7a:812cbe55:fcadf3ca Events : 25 Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 - 0 0 1 removed 1 8 19 - faulty /dev/sdb3
Determine MD array status using exit code.
$ sudo mdadm --detail --test /dev/md1 1>/dev/null
$ echo $?
1
Exit code 1
means that array is functioning in degraded state as at least one device failed.
Third case
Determine MD array status.
$ sudo mdadm --detail /dev/md1
/dev/md1: Version : 1.2 Creation Time : Sun May 29 23:13:51 2022 Raid Level : raid0 Raid Devices : 3 Total Devices : 1 Persistence : Superblock is persistent Update Time : Sun May 29 23:13:51 2022 State : active, FAILED, Not Started Active Devices : 1 Working Devices : 1 Failed Devices : 0 Spare Devices : 0 Layout : original Chunk Size : 512K Consistency Policy : unknown Name : milosz.wtf:1 (local to host milosz.wtf) UUID : 1cb29db7:daed3f72:f9e99802:20103e93 Events : 0 Number Major Minor RaidDevice State - 0 0 0 removed - 0 0 1 removed - 0 0 2 removed - 7 8 2 sync /dev/sdc3
Determine MD array status using exit code.
$ sudo mdadm --detail --test /dev/md1 1>/dev/null
$ echo $?
2
Exit code 2
means that array is unusable due to multiple failed devices.