What is Differential Backup?

When it comes to backup strategies, one common approach is differential backup – but what exactly sets it apart from other types of backup and recovery services? Let’s explore the characteristics and benefits of differential backup and how it compares to other backup methods.

What is Differential Backup?

Differential backup is a data backup procedure that records data changes that have occurred since the most recent full backup. Differential backup only saves the new data or data that has changed since the last full backup; it does not make a backup of all the data every single time. The benefit of using differential backup, versus a full or incremental backup, is that it takes a relatively shorter amount of time to restore the data. However, if done several times without occasionally performing a full backup, the size of the differential backup can grow larger than the baseline full backup.

How does it work?

Differential backups start with an initial full backup, which is the process of making a copy of all objects in a file system used to store data. Once the first full backup is performed, differential backups use it for comparison when they carry out subsequent backups. As files are created or changed before the next full backup, they’re flagged. Organizations set their differential backup schedule and once initiated, the cumulative backup data is copied.

For example, if a full backup is done on Sunday, Monday’s differential backup duplicates all the files changed or added since Sunday’s full backup. The differential backup performed on Tuesday then backs up all the changed files since Sunday’s full backup, including the files changed on Monday. This process continues daily.

If a complete restore is needed at some point in time, only the last full backup and latest differential backup are required.

Why use differential backups?

Differential backups are used for various objectives and provide benefits in specific conditions. Here are some of the benefits of using differential backups:

• Faster Backup Creation: One of the key benefits is their ability to create backups quickly. They are often faster to make than full backups since they only record changes made since the last full backup. This can be especially useful for organizations with short backup periods or big data volumes.
• Quicker Data Restoration: When restoring data, differential backups are faster than full backups because we just require the first full backup and the most recent differential backup. This can assist in reducing downtime and get our systems back up and running more quickly.
• Reduced Backup Storage: While differential backups accrue over time, they nevertheless take up less storage space than regular full backups. This can save money on storage costs, especially when compared to keeping numerous complete backups.
• Simplified Backup Management: Managing a backup chain with differential backups is easier than managing a chain of incremental backups. With differentials, we just need to keep track of the first complete backup and the most current differential, making backup administration simpler.
• Ideal for Certain Recovery Scenarios: Differential backups can be very beneficial in some recovery circumstances, such as when we wish to restore our data to a precise point in time between complete backups. This provides greater flexibility in data recovery.
• Balanced Approach: Differential backups offer a middle-ground solution between the storage economy of incremental backups and the ease of complete backups. When our organization’s backup requirements lie between these two extremes, they can be a smart compromise.

However, differential backups have disadvantages, such as the potential for longer Recovery Point Objectives (RPOs) compared to incremental backups and the accumulation of data over time, which can result in bigger backup files. Our backup approach should be tailored to our individual data security requirements, taking into account elements such as data change frequency, available storage space, and recovery time targets. To fulfill their unique backup and recovery demands, organizations frequently utilize a variety of backup solutions, including full, differential, and incremental backups.

What is the difference between incremental and differential backup?

Incremental backups are very similar to differential backups, but there is a major difference between the two.

As we’ve previously covered, differential backups contain the changes that were made since the previous full backup. Meanwhile, with an incremental backup, each ensuing backup contains only the adjustments that have been made since the previous backup, whether that backup was a full backup or differential.

So, because incremental backups may copy fewer files than a differential backup would, they, therefore, can also take up less storage space because of it.

Conclusion

Differential backup provides a valuable backup strategy that balances backup speed and storage efficiency. By capturing changes made since the last full backup, it offers faster data backup and recovery while requiring less storage space than full backups. However, it’s important to consider factors such as backup size and restore times when deciding on the most suitable backup strategy for your needs.