How to Create RAID 10 in Linux

If you’re looking for a balance of speed, reliability, and storage capacity for your Linux system, RAID 10 might be the perfect solution for you. RAID 10 combines the best of RAID 1 (mirroring) and RAID 0 (striping) to give you a fault-tolerant and high-performance storage solution. In this tutorial, we’ll guide you through creating a RAID 10 array in Linux using the mdadm tool.

Prerequisites

Before we begin, you’ll need:

A Linux system (we’ll be using Ubuntu in this tutorial, but the process is similar for other distributions)
Four or more storage devices (hard drives or SSDs) of the same size

Step 1: Install mdadm

First, you’ll need to install the mdadm tool. On Ubuntu, you can do this by running:

sudo apt-get update
sudo apt-get install mdadm

For other Linux distributions, consult their respective package managers (e.g., yum for Fedora or zypper for openSUSE).

Step 2: Prepare the Storage Devices

To create a RAID 10 array, you’ll need to partition your storage devices. For this tutorial, we assume that you have four storage devices with device names /dev/sdb, /dev/sdc, /dev/sdd, and /dev/sde. Replace these names with the appropriate device names on your system.

Use the fdisk utility to create partitions on each device:

sudo fdisk /dev/sdb

In the fdisk utility, follow these steps:

Press n to create a new partition.
Press p for a primary partition.
Press 1 to create the first partition on the device.
Press Enter twice to accept the default start and end sector values.
Press t to change the partition type.
Enter fd to set the partition type to Linux RAID autodetect.
Press w to write the changes and exit.

Repeat this process for the remaining devices: /dev/sdc, /dev/sdd, and /dev/sde.

Step 3: Create the RAID 10 Array

Now that the storage devices are prepared, it’s time to create the RAID 10 array using the mdadm command:

sudo mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1

This command creates a RAID 10 array named /dev/md0 using the four partitions we created in the previous step. Adjust the number of --raid-devices and device names as needed for your configuration.

Step 4: Save the RAID Configuration

After creating the RAID 10 array, you’ll want to save its configuration to ensure it’s recognized at system startup:

sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf

This command appends the RAID configuration to the mdadm.conf file.

Next, update your system’s initial RAM disk to include the RAID configuration:

sudo update-initramfs -u

Step 5: Create a Filesystem on the RAID Array

Now it’s time to create a filesystem on the RAID array. In this example, we’ll create an ext4 filesystem:

sudo mkfs.ext4 /dev/md0

You can choose a different filesystem type depending on your requirements (e.g., XFS or Btrfs).

Step 6: Mount the RAID Array

Create a mount point for the RAID array:

sudo mkdir /mnt/raid10

Mount the RAID array to the newly created mount point:

sudo mount /dev/md0 /mnt/raid10

To ensure the RAID array is mounted automatically at startup, add an entry to the /etc/fstab file:

echo '/dev/md0 /mnt/raid10 ext4 defaults 0 0' | sudo tee -a /etc/fstab

Replace ext4 with the filesystem type you chose in Step 5.

Final Thoughts

Congratulations! You’ve successfully created a RAID 10 array in Linux using the mdadm tool. RAID 10 provides a combination of speed and redundancy, making it an excellent choice for many use cases. Be sure to explore other RAID configurations How to Create RAID 5 in Ubuntu and How to Create RAID 1 in Ubuntu