Creating a software RAID on Ubuntu/Debian

Posted 24/11/2015 by Chris & filed under Linux & Unix.

Creating a software raid of disks is quite easy in Ubuntu, I will assume the disks are attached (physically or virtually) to the guest operating system.

Currently Ubuntu supports the following raid levels:

RAID level 0
RAID level 1
RAID level 2
RAID level 3
RAID level 4
RAID level 5
RAID level 6
RAID level 10
RAID level 50
RAID level 0+1

In this example I am using sdb1 and sdc1 disks and settings the raid to a mirror (1) with a total mirrored size of 4TB (3906885440K)

Install mdadm (if not already installed)

apt-get update &amp;&amp; apt-get install -y mdadm

1	apt-get update && apt-get install -y mdadm

Run mdadm to create the mirror

mdadm --create --verbose /dev/md0 --raid-device=2 --level=1 /dev/sdb1 /dev/sdc1

1	mdadm --create --verbose /dev/md0 --raid-device=2 --level=1 /dev/sdb1 /dev/sdc1

mdadm_create_raid1

Run mkfs.ext3 to create a ext3 filesystem on the mirror volume

mkfs.ext3 /dev/md0

1	mkfs.ext3 /dev/md0

mkfs.ext3_dev_md0

Mount the mirror by creating a mount point and running mount to mount the md0 volume

mkdir /mnt/raid1
mount /dev/md0 /mnt/raid1

1 2	mkdir /mnt/raid1 mount /dev/md0 /mnt/raid1

mount_raid1

Check to see if you can see the mirror

df -h

1

df -h

df_h_raid1

Check the status of the build

cat /proc/mdstat

1	cat /proc/mdstat

mdadm_raid_build_cat_proc

Add to fstab to auto mount on startup

vi /etc/fstab
/dev/md0 /mnt/raid1 ext3 defaults 0 0

1 2	vi /etc/fstab /dev/md0 /mnt/raid1 ext3 defaults 0 0

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