Configure "Raid 6" in Linux

Configuring RAID 6 in Linux involves combining multiple disks into a single RAID array that provides both data striping and double distributed parity. RAID 6 offers greater fault tolerance compared to RAID 5 by allowing for the simultaneous failure of up to two disks without losing data. Here’s a step-by-step guide to configure RAID 6 using mdadm on a Linux system, including CentOS 9:

Note:The minimum no of disk required to implement raid 6 is 4.

Step-by-Step Guide to Configure RAID 6

Step 1: Install Required Packages

Ensure mdadm (the utility for managing RAID arrays) is installed on your Linux system. Use the package manager appropriate for your distribution. For CentOS 9, you can use:

sudo dnf install mdadm

Step 2: Identify Disks

Identify the disks you want to use for RAID 6. For this example, assume you have four disks: /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd.

Step 3: Partition Disks

If your disks are new or need reconfiguration, partition them accordingly. You can use tools like fdisk, parted, or gdisk to create partitions on each disk. Ensure partitions are of equal size across all disks.

For example, partition /dev/sda:

sudo fdisk /dev/sda

Create a new partition (e.g., /dev/sda1) covering the desired space. Repeat this for /dev/sdb, /dev/sdc, and /dev/sdd.

Step 4: Create RAID 6 Array

Create the RAID 6 array using mdadm. RAID 6 requires a minimum of four disks:

sudo mdadm --create /dev/md0 --level=6 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

• /dev/md0 is the name of the RAID device.

• --level=6 specifies RAID level 6 (striping with double distributed parity).

• --raid-devices=4 specifies the number of devices in the RAID array (in this case, four disks).

• /dev/sda1, /dev/sdb1, /dev/sdc1, and /dev/sdd1 are the partitions created earlier on /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd.

Step 5: Verify RAID Configuration

Check the status of the RAID array to ensure it was created successfully:

sudo mdadm --detail /dev/md0

This command provides detailed information about the RAID array md0, including its status, devices, and RAID level.

Step 6: Create a Filesystem

Next, create a filesystem on the RAID array. For example, to create an ext4 filesystem:

sudo mkfs.ext4 /dev/md0

Step 7: Mount the RAID Array

Create a mount point and mount the RAID array:

sudo mkdir /mnt/raid6
sudo mount /dev/md0 /mnt/raid6

Step 8: Configure Mount at Boot

To ensure the RAID array mounts automatically at boot time, add an entry to /etc/fstab:

echo '/dev/md0   /mnt/raid6   ext4   defaults   0 0' | sudo tee -a /etc/fstab

Step 9: Test and Verify

Reboot your system to test if the RAID array mounts automatically and correctly. After rebooting, verify that the RAID array is still operational:

sudo mdadm --detail /dev/md0

Ensure that all disks (/dev/sda1, /dev/sdb1, /dev/sdc1, /dev/sdd1) are active and in sync (U state).

Additional Notes:

• Always replace /dev/sda1, /dev/sdb1, /dev/sdc1, /dev/sdd1, etc., with the appropriate partitions on your disks.

• Customize RAID level (--level), RAID device name (/dev/md0), filesystem type (ext4), and mount point (/mnt/raid6) as per your requirements.

• RAID 6 provides higher fault tolerance compared to RAID 5 by allowing for the simultaneous failure of up to two disks without data loss.

• Monitor the RAID array regularly (sudo mdadm --detail /dev/md0) to ensure all disks are functioning properly and to detect any potential issues early.

By following these steps, you can successfully set up RAID 6 on CentOS 9 (or any Linux distribution) using mdadm, providing robust data protection and performance for your storage solution.