Raid How-To

How to setup and configure Raid devices

Scan Devices and Start Raid

This helps when not /dev/md0 has been found:

mdadm --assemble --scan

Check the device for errors:

e2fsck -f /dev/md2

Resize the file system and make it a little smaller than necessary:

resize2fs /dev/md2 25G

Resize the Raid device:

mdadm --grow /dev/md2 --size=33554432

Resize the file system to the maximum:

resize2fs /dev/md2

Check the file system again:

e2fsck -f /dev/md2

Remove one partition from the Raid:

mdadm /dev/md2 --fail /dev/sdb4

Stop the Raid array:

mdadm --stop /dev/md2

Resize the partitions using fdisk or gdisk. Run partprobe to refresh the partition table to the kernel. Add the partition to the raid array:

mdadm --zero-superblock /dev/sdb4
mdadm -a /dev/md2 /dev/sdb4

Watch the resync:

cat /proc/mdstat

Create a new raid 1:

mdadm --create --verbose /dev/md3 --level=mirror --raid-devices=2 /dev/sda5 /dev/sdb5

Delete Raid volume

umount /mnt/raidvolume
mdadm --stop /dev/md0
mdadm --zero-superblock /dev/sda4
# remove /mnt/raidvolume in /etc/fstab
# remove raidvolume in /etc/mdadm/mdadm.conf