Creating Software RAID0 (Stripe) on ‘Two Devices’ Using ‘mdadm’ Tool in Linux

RAID stands for Redundant Array of Inexpensive Disks. It is a data storage technique that allows users to combine multiple disks into a single logical unit to provide performance, reliability, and storage capacity. RAID 0 (Stripe) is one of the RAID levels that uses striping to write data across multiple disks.

In this article, we will learn how to create RAID 0 on two devices using the mdadm tool in Linux.

What is RAID 0?

RAID 0, also known as striping, is a RAID level that combines multiple disks into a single logical unit. Data is divided and written across all disks in the array, allowing for faster data access and transfer speeds. RAID 0 does not offer any redundancy, so if one disk fails, all data is lost. However, since data is striped across multiple disks, the likelihood of a single disk failure is reduced.

One of the main benefits of RAID 0 is its improved performance. Since data is written across multiple disks, read and write operations can be performed simultaneously, resulting in faster data transfer rates. RAID 0 is commonly used in applications that require high performance, such as video editing and gaming.

Prerequisites

Before we begin, make sure that you have the following prerequisites −

• Two disks with the same size and speed

• A Linux machine with root access

• mdadm tool installed

Creating RAID 0 on two devices

Follow the steps given below to create RAID 0 on two devices using the mdadm tool in Linux.

Step 1: Identify the Disks

The first step is to identify the disks that we will be using for RAID 0. To identify the disks, use the following command −

sudo fdisk -l

This command will show you all the disks attached to your system. In our case, we will be using /dev/sdb and /dev/sdc.

Step 2: Install mdadm Tool

To create RAID 0, we need to install the mdadm tool if it is not already installed. Use the following command to install it −

sudo apt-get install mdadm

Step 3: Create RAID 0

Now we are ready to create RAID 0 using the mdadm tool. Use the following command −

sudo mdadm --create /dev/md0 --level=stripe --raid-devices=2 /dev/sdb /dev/sdc

In the above command, we are creating RAID 0 with the name /dev/md0 using two devices (/dev/sdb and /dev/sdc). The --level=stripe option specifies that we are creating RAID 0. The --raid-devices=2 option specifies the number of devices that we are using.

Step 4: Format the RAID 0 Array

Once the RAID 0 array is created, we need to format it with a file system. In this example, we will use the ext4 file system. Use the following command to format the RAID 0 array −

sudo mkfs.ext4 /dev/md0

Step 5: Mount the RAID 0 Array

After formatting the RAID 0 array, we need to mount it to a mount point so that we can use it. Use the following command to create a mount point −

sudo mkdir /mnt/raid0

Now, mount the RAID 0 array to the mount point using the following command −

sudo mount /dev/md0 /mnt/raid0

Step 6: Configure mdadm to Automatically Assemble RAID 0

By default, the mdadm tool will not automatically assemble the RAID 0 array after a system reboot. To configure it to automatically assemble the RAID 0 array on boot, use the following command −

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

This command will save the RAID configuration to the /etc/mdadm/mdadm.conf file.

Step 7: Test the RAID 0 Array

To test the RAID 0 array, create a file on the mount point and check if the file is distributed across both disks using the following command −

sudo dd if=/dev/zero of=/mnt/raid0/testfile bs=1M count=100

This command will create a 100MB file named testfile on the RAID 0 array. Once the file is created, use the following command to check if the file is distributed across both disks −

sudo mdadm --detail /dev/md0

This command will display detailed information of the RAID 0 array, including the RAID level, number of devices, and their status. You can check if the file is distributed across both disks by verifying the "Device Role" column. It should show "Data" for both disks, indicating that the file is distributed across both disks in the RAID 0 array.

Step 8: Automount the RAID 0 Array

If you want the RAID 0 array to be mounted automatically at system startup, you need to add an entry for it in the /etc/fstab file. Open the file using the following command −

sudo nano /etc/fstab

Add the following line to the end of the file −

/dev/md0 /mnt/raid0 ext4 defaults 0 0

Save and close the file.

Step 9: Verify the RAID 0 Array

To verify that the RAID 0 array is working correctly, you can use the mdadm --monitor command. This command will monitor the status of the RAID 0 array and send email alerts if there is a problem.

To set up email alerts, you need to configure the mail server on your system. Once the mail server is set up, you can use the following command to start monitoring the RAID 0 array −

sudo mdadm --monitor --scan --test --oneshot

This command will send a test email to the email address configured in the mail server.

RAID 0 best practices

When using RAID 0, it is important to keep in mind that there is no redundancy. This means that if one disk fails, all data is lost. To minimize the risk of data loss, it is recommended to use high-quality disks with a low failure rate. It is also important to monitor the health of the disks and replace any disks that show signs of failure.

RAID 0 should not be used for applications that require high reliability or data protection, such as financial or medical data storage. It is best suited for applications that require high performance, such as gaming or video editing.

It is also important to regularly back up data stored on RAID 0 arrays to an external storage device or cloud storage service. This ensures that data can be recovered in the event of a catastrophic failure.

Conclusion

RAID 0 is a high-performance RAID level that uses disk striping to provide improved storage capacity and faster read and write speeds. It is a good option for non-critical data storage that requires high performance, such as gaming, video editing, and rendering. Compared to other RAID levels, RAID 0 provides the best performance, but it lacks redundancy and data protection. Therefore, it is not recommended for critical data storage.

In order to use RAID 0 effectively, it is important to follow best practices such as using disks with the same size and speed, keeping backups of important data, and monitoring the RAID array regularly for any issues. Additionally, it is important to understand the limitations of RAID 0 and to use it in conjunction with other data protection measures, such as regular backups and redundancy, to ensure the safety of your data. Overall, RAID 0 is a powerful tool for high-performance data storage, but it must be used responsibly and with caution.