Practical steps to inspect and troubleshoot Linux software RAID using mdadm. 11.01.2026 | reading time: 2 min When a RAID array misbehaves the quickest way to get facts is the command-line: mdadm gives the admin a clear picture of array state, member health and events to act on. Hands-on check Follow these exact commands to inspect an array and see typical output: ```bash\n# show kernel RAID status\ncat /proc/mdstat\nPersonalities : [raid1]\nmd0 : active raid1 sdb1[1] sda1[0]\n 104320 blocks [2/2] [UU]\n\n# detailed array info\nmdadm --detail /dev/md0\n/dev/md0:\n Version : 1.2\n Creation Time : Tue Jun 10 12:34:56 2025\n Raid Level : raid1\n Array Size : 104320 (101.78 MiB 106.74 MB)\n Used Dev Size : 104320 (101.78 MiB 106.74 MB)\n Raid Devices : 2\n Total Devices : 2\n State : active\n Active Devices : 2\n Working Devices : 2\n Failed Devices : 0\n``` Key commands and flags Start with `cat /proc/mdstat` for a quick glance and then run `mdadm --detail /dev/mdX` to see roles, sync status and events; use `mdadm --examine /dev/sdX` to check superblocks on a device and `mdadm --monitor` for live notifications. Repair and rebuild steps If a disk failed mark it failed and remove it with `mdadm --manage /dev/mdX --fail /dev/sdY` and `mdadm --manage /dev/mdX --remove /dev/sdY`, then add a replacement with `mdadm --manage /dev/mdX --add /dev/sdZ`; watch the rebuild progress with `cat /proc/mdstat` or `mdadm --detail`. Complementary utilities Beyond mdadm, check device health with `smartctl` before rebuilding; use `lsblk` and `udevadm` to verify device names and persistent paths; integrate `mdadm --monitor` with systemd or an email script to get early warnings. Next steps and certification Practice these commands in a safe lab, simulate failures and rebuilds, then automate monitoring; to deepen skills consider formal certification and focused exam prep at bitsandbytes.academy for CompTIA Linux+ or LPIC-1. Join Bits & Bytes Academy First class LINUX exam preparation. storage utilities backup troubleshooting infrastructure
