How to set up RAID 1

What Is a RAID Setup

RAID (Redundant Array of Independent Disks) is a storage configuration method that employs different techniques for data storage. There are different types of RAID storage setups, generally referred to as “Arrays.” A Raid Array is a type of RAID storage configuration that employs specific techniques for data storage; popular ones are RAID 0, RAID 1, RAID 5, RAID 6, and RAID 01/10.

Generally, each RAID array employs one technique such as mirroring, striping, or parity, or combines any two of these techniques. The essence of RAID setups is to create large storage by combining multiple storage hard drives (SSD or HDD). The numerical values are used to identify the RAID array or level, the numbers hold no other significance.

Switching to a RAID level from a single-drive storage can provide good protection against data loss. This is because some RAID levels offer high redundancy and resilience; the storage will still be fully functional even when one hard drive fails. But then, no RAID level can be used as a full substitute for traditional data backups.

System Requirements for RAID 1

To set up RAID 1 on your computer, the system must meet specific requirements. RAID 1 can run on Windows or Linux OS.

Windows OS:

• Windows OS 7 to 11 or Windows Server 03 – 09.
• Your PC must support Intel Rapid Storage Technology
• Minimum of two hard drives (preferably hard drives of the same capacity and performance rating).
• Hardware RAID controller or RAID management software (for software RAID)
• Ensure your system has sufficient processing power and memory (16GB RAM is decent)

Linux OS:

• Linux distro capable of running a RAID server
• RAID management software
• At least two hard drives of the same capacity and performance
• RAID drivers to help the OS detect your hardware RAID controller

How to Set Up Software RAID 1 on Windows and Linux

Here’s a step-by-step guide on how to set up RAID 1 configuration on a Windows or Linux OS computer.

1. Format Hard Drive

First things first, you have to decide on how many hard drives you wish to use for the setup. Bear in mind that the total capacity a RAID 1 would offer is directly proportional to the total capacity of the smallest hard drive you use. So, it is best to use hard drives of the same storage capacity.

You need a minimum of two drives, but you can use up to six (6) or more drives. While choosing hard drives of the same storage capacity, also pay attention to the interfaces of the drives. If you use a SATA 6Gb/s drive and a SATA 3Gb/s, the RAID will perform at a speed of 3Gb/s. To be on the safe side, use the same-specked hard drives.

With the hard drive decisions made, then you can proceed. Apparently, you will have to format the hard drives, so if you have any data saved on them previously, you should back it up before proceeding.

2. Install mdadm

Depending on your Linux distro, you can install the mdadm utility from the package manager: “sudo apt-get install mdadm”. Or, you can use the “sudo yum install mdadm” command to install with YUM on CentOS or any other Red Hat-based distributions. The mdadm utility makes it easy to create RAID 1 on Linux using a simple command, mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

3. Create RAID 1 Logical Drive

For Windows OS users who want to run software RAID 1, you need to find out what Windows calls RAID. In newer Windows editions, RAIDs are referred to as “Storage Spaces,” and you can find this setting from the control panel. But to make it easier, hit the Search bar on your taskbar and search for Storage Spaces.

• When the utility pops up, click on Create a New Pool and Storage Space, and grant admin access if prompted.
• Select the hard drives you want to use in creating the RAID 1 and click on “Create Pool.”
• Name your pool and assign a drive letter. Also, set the file system for your RAID to NTFS.
• In the Resilience Type, click the drop-down and select “Two-way Mirror.”
• Confirm if you’d like to make any further changes to the settings shown to you, then click on “Create Pool” when you’re done.

Explain the steps to create a RAID 1 logical drive, detailing the process for both Windows Disk Management and the mdadm command on Linux. For Linux OS users, the command to create a RAID 1 array is mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1. This command will create RAID 1 with the two selected disks.

4. Create a File System on the RAID 1 Logical Drive

When you set up RAID 1 on a Linux distro, you need to create and assign a filesystem to the RAID array. The procedure to create and mount a new filesystem for your RAID 1 on Linux is clearly outlined below.

• Create a filesystem (ext4) for your RAID: $ sudo mkfs.ext4 -F /dev/md0
• Create a mount point for the new filesystem: $ sudo mkdir -p /mnt/md0
• Now, mount the filesystem using this command: $ sudo mount /dev/md0 /mnt/md0
• Confirm if the new space you created is available: $ df -h -x devtmpfs -x tmpfs

This will confirm and show if the new filesystem is mounted and accessible, and then you’re good to go.

Additionally, to save the array layout so that it automatically reassembles on boot, follow the steps below:

• Scan the array and add this file: sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf
• Update the initial RAM file system: sudo update-initramfs –u
• Place the filesystem mount options to the /etc/fstab file: echo '/dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab

Once this is done, your RAID 1 will automatically assemble and mount at each boot. You won’t have to manually reassemble the layout.

5. Test RAID 1

Done with the setup? You will need to test your RAID 1 to ensure that you got everything correctly. To do that, you need to create a text file in /mnt/raid1

• $ /mnt/raid1
• sudo nano raid1.txt

Give the file a name to always remember it, then save and close. Now, disconnect one of the RAID drives and check the status of your RAID 1.

• sudo mdadm --examine /dev/sda1 /dev/sdb1

The output should show that one of the RAID drives is offline – that shows you did the setup pretty well. To get details of the offline drive, use this command:

• sudo mdadm --detail /dev/md0

Can I Create a RAID 1 Array With a Drive that Already has Data?

The simple answer is no. But, you can format the drive to remove all data saved on it, and then proceed to add it to your RAID array. One of the steps to creating a RAID level is to format the drive(s), which erases every data on the drive(s). If you insert a drive with data into your RAID array to replace a failing drive, you stand a chance of losing all the data on that drive.

So, to be on the safe side, run a full backup to clone all the files and data you have on the said drive, then format the drive and use it for RAID 1. Anytime you decide to stop using the drive for your RAID, you can disconnect it and restore its previous files from the backup you made earlier. Anything else aside from this procedure will make you lose your files on the said drive.