Disk mirroring is a preservation technique that duplicates data to other hard drives as it is written. For example, when you save a picture into a computer, the data is automatically duplicated to other hard drives connected to the same computer or network. If one disk gets corrupted, you can still retrieve the file from the mirrored hard drives. The technique helps ensure there is always a backup of any data written to a disk.

In disk mirroring, the hard drives are connected to one another through a disk controller card, an electrical computer component that enables hard drives to communicate with each other. Disk mirroring is also called “Redundant Array of Independent Disks 1 (RAID 1).”

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When shooting conversation and action scenes in movies, directors often use two or more cameras to ensure they are captured well. The strategy lessens the risk of reshooting scenes in case some angles are unclear. Disk mirroring works similarly.

As you create files and make changes to documents, the data is simultaneously reflected in mirrored drives. The image below shows a simple representation of disk mirroring.

Disk Mirroring

What Is the Purpose of Disk Mirroring?

The primary purpose of disk mirroring is to protect a computer owner from data loss stemming from disk failures, data recovery issues, disasters, and other reasons. Therefore, disk mirroring is a form of data backup but it is done in real-time, reducing the need for regular manual creation of data backups.

How Is Disk Mirroring Set Up?

Disk mirroring can be set up using an online connection. Another hard drive in a different location or computer is configured to get updated with data from another disk through the Internet. Most of the time, the second drive is located in an entirely different place to avoid data loss due to fire and other disasters.

Another method to set up disk mirroring is through using RAID, which could be the most popular among institutions.

What Is RAID?

An integral concept in disk mirroring is RAID, which is a way of grouping different disks together. The interconnected disks form a larger hard drive referred to as a “RAID set.” There are different RAID levels or types of RAID sets, and disk mirroring uses RAID 1. Another typical RAID level is RAID, also known as “disk striping.”

What Is the Difference between Disk Mirroring and Disk Striping?

While disk mirroring entails simultaneously copying the entire data to other hard drives, disk striping works differently. In disk striping, data is segmented into multiple blocks, and each component is stored across multiple drives.

As you may imagine, disk mirroring could be slower than disk striping since the whole data is copied in real-time instead of distributing smaller chunks to different disks. However, disk striping may not be as reliable. When one drive crashes or gets corrupted, all of the data could be lost.

Advantages and Disadvantages of Disk Mirroring

Disk mirroring is easy to implement. All you need is a disk controller card to connect multiple hard drives or an Internet connection to link disks in different locations. Moreover, all data remains accessible even when one drive fails. Data can simply be copied from one of the mirrored disks to the replacement drive.

Still, there are downsides to disk mirroring that have to be considered. For one, the data storage capacity is reduced in half since data is being copied completely, making them redundant. For example, saving 5GB of data would take up 10GB of space. That leads to another disadvantage—the cost involved. You would need twice the number of hard drives to store a specific volume of data.

The logic and purpose behind disk mirroring are as simple as it sounds. It simply means having the replica of any data on a different disk so that you have a backup in case one hard drive fails. You may even be applying the concept if your phone is set up to automatically sync photos, contacts, and other files to cloud platforms, such as Google Drive and iCloud.