Identity

Kernel modules: md_mod, raid0, raid1, raid456, raid10 (auto-loaded on array use)
CLI tool: mdadm
Config: /etc/mdadm/mdadm.conf (Debian/Ubuntu), /etc/mdadm.conf (RHEL/Fedora)
Status file: /proc/mdstat — live array state, rebuild progress, sync speed
Logs: journalctl -k | grep -i md, /var/log/syslog or /var/log/messages
Distro install: apt install mdadm / dnf install mdadm

Key Operations

Operation	Command
Check array status (summary)	`cat /proc/mdstat`
Check array status (detail)	`mdadm --detail /dev/md0`
Check individual disk superblock	`mdadm --examine /dev/sdb1`
Create RAID-1 array	`mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1`
Create RAID-5 array	`mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1`
Create RAID-6 array	`mdadm --create /dev/md0 --level=6 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1`