RAID

Motherboard RAID sucks, software RAID is far better for personal usage and small structures. This section will only discuss mdadm solution which is a software RAID tools. It supports multiple kind of RAID, ranging from RAID-0 to RAID-6 or more exotic ones.

Configure partitions

Manage partitions. You may want to refer to MBR before applying any changes to partitions.

root@server: fdisk -L #list partitions and disks
root@server: fdisk /dev/sdX #change a partition
root@server: sfdisk -d /dev/sdb | sfdisk /dev/sdc #copy sdb partition table to sdc

Configure RAID-1

Setup mdadm

root@server: apt-get install mdadm

Create RAID

root@server: mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

You can use missing instead of any /dev/sdX if a disk is missing. Safety disks can also be configured by addind --spare=1 to the command.

Watch RAID status

root@server: cat /proc/mdstat
root@server: watch -n 1 cat /proc/mdstat

Format array

root@server: mkfs.ext4 /dev/md1

Save configuration for next restart

root@server: mdadm --detail --scan --verbose > /etc/mdadm/mdadm.conf

This command must be run after every modification of the RAID structure or definition.

Edit /etc/fstab to mount the RAID automatically. Prefer using UUID when mounting disks in fstab. This technique is safer than specifying the name because it can changed whereas UUID cannot.

root@server: ls -l /dev/disk/by-uuid/

Check partition status by checking the file /proc/mdstat. Using smartctl can help you to prevent disk failures.