Scan a system for RAID arrays and save findings so the array reappears across reboots:
1 | # mdadm --detail --scan && /etc/mdadm/mdadm.conf |
Create a RAID5 array out of sdm1, sdj1, and a missing disk (all partitioned with raid-autodetect partitions)
1 | # mdadm --create /dev/md1 --level=5 --raid-devices=3 /dev/sd[mj]1 missing |
Create a RAID1 array
1 | # mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sd[ts]1 |
Remove a RAID array
1 2 | # mdadm --stop /dev/md1 # mdadm --zero-superblock /dev/sd[ts]1 |
Replace a failed drive that has been removed from the system
1 | # mdadm /dev/md3 --add /dev/sdc1 --remove detached |
Add a new drive to an array, and remove an existing drive at the same time
1 | # mdadm /dev/md0 --add /dev/sda1 --fail /dev/sdb1 --remove /dev/sdb1 |
Add a drive to a RAID 5 array, growing the array size
1 2 | # mdadm --add /dev/md1 /dev/sdm1 # mdadm --grow /dev/md1 --raid-devices=4 |
Fixing an incorrect /dev/md number (ie /dev/md127)
1. Remove any extra parameters for the array except for UUID in /etc/mdadm/mdadm.conf. Ex.
1 2 | #ARRAY /dev/md1 level=raid1 num-devices=2 metadata=1.2 UUID=839813e7:050e5af1:e20dc941:1860a6ae ARRAY /dev/md1 UUID=839813e7:050e5af1:e20dc941:1860a6ae |
2. Then rebuild the initramfs
1 | sudo update-initramfs -u |