How to do Software Raid 10

Creating a RAID 6 Array

Software RAID 10, also known as RAID 1+0, is a combination of RAID 1 (mirroring) and RAID 0 (striping). It provides both fault tolerance and improved performance by striping and mirroring data across multiple disks. This RAID level is commonly referred to as a nested or hybrid RAID.

Key features of Software RAID 10 include:

1. Mirroring (RAID 1): In RAID 10, data is mirrored across pairs of disks. Each disk in a pair contains an exact copy of the data stored on the other disk. This provides redundancy and fault tolerance.
2. Striping (RAID 0): The mirrored pairs are then striped together, meaning data is distributed across multiple pairs of disks. This striping enhances performance by allowing parallel read and write operations.
3. Fault Tolerance: RAID 10 can withstand the failure of one or more disks, depending on which disks fail. As long as at least one disk in each mirrored pair is operational, the array remains functional.
4. Usable Capacity: The usable capacity of RAID 10 is approximately half of the total capacity due to mirroring. For example, in a four-disk RAID 10 array, only half of the total capacity is available for storing data.
5. Performance: RAID 10 provides good read and write performance, especially for random I/O operations. This makes it suitable for applications that require a balance of performance and data protection.
6. Rebuild Performance: In the event of a disk failure, the rebuild process in RAID 10 is generally faster compared to other RAID levels like RAID 5 or RAID 6. This is because the data can be copied from the mirror of the failed disk.
7. Cost: RAID 10 is considered more expensive than some other RAID configurations due to the need for a larger number of disks to achieve redundancy.

Software RAID 10 is commonly used in critical environments where both performance and fault tolerance are crucial, such as database servers and high-performance computing systems.

Creating a Software RAID 10 array involves combining RAID 1 (mirroring) and RAID 0 (striping) to achieve both fault tolerance and improved performance. Below are the steps to set up a Software RAID 10 array using the mdadm tool on a Linux system:

Setting Up Software RAID 10 with mdadm

1. Install mdadm:

   sudo apt-get update sudo apt-get install mdadm

2. Identify Disks: Use the following command to identify the disks you want to include in the RAID 10 array (e.g., /dev/sda, /dev/sdb, /dev/sdc, /dev/sdd).

   lsblk

3. Create RAID 10 Array:

   sudo mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

   This command creates a RAID 10 array named /dev/md0 with four devices (/dev/sda1, /dev/sdb1, /dev/sdc1, /dev/sdd1).

4. Check Array Status:

   cat /proc/mdstat

   Verify the status of the RAID array. It may take some time for the array to synchronize.

5. Create File System:

   sudo mkfs.ext4 /dev/md0

   Create a file system on the RAID array.

6. Mount the Array:

   sudo mkdir /mnt/raid10 sudo mount /dev/md0 /mnt/raid10

   Mount the RAID array to a directory of your choice.

7. Update fstab (Optional):

   sudo nano /etc/fstab

   Add the following line to automatically mount the RAID array on system boot:

   /dev/md0 /mnt/raid10 ext4 defaults 0 0

8. Test the Array: Copy some files to the RAID array and check if it functions as expected.

Remember to replace /dev/sda1, /dev/sdb1, /dev/sdc1, and /dev/sdd1 with the actual disk partition names on your system. Customize mount points and file system types based on your preferences. RAID 10 provides both fault tolerance and improved performance, making it suitable for critical systems.