What is Differential Backup? A Complete Guide to Data Protection

Data backup is a fundamental part of protecting yourself against the dangers of the digital landscape. Hardware failure, cyberattacks, and accidental deletion are just some of the methods that can all play havoc with your files. Backing up this data is critical to ensure business continuity in the event of an error, system failure, or ransomware attack.

One effective backup strategy is differential backup. But what does this mean and how does it work compared to the alternatives?

What is differential backup?

A differential backup is a type of backup that only records the changes made since the last full backup. This means that when you run a differential backup, only data that has changed since the last full backup will be saved, rather than copying the entire system.

Here’s an example. Say you performed a full backup on a Sunday:

• Monday’s differential backup saves any changes made since Sunday.
• Tuesday’s differential backup saves any changes made on Monday and Tuesday.
• Wednesday’s differential backup continues accumulating all the changes made since Sunday, and so on.

In short, a differential backup will keep growing with each day until another full backup is performed.

Differential backup vs. incremental backup

A differential backup is different to an incremental backup in one key aspect. In an incremental backup, only the changes made since the last backup are saved. Let’s use the same example as above.

As in the previous example, say you performed a full backup on a Sunday:

• Monday’s incremental backup saves any changes made since Sunday.
• Tuesday’s incremental backup only saves the changes made since Monday’s incremental backup.
• Wednesday’s incremental backup only saves the changes made since Tuesday’s incremental backup, and so on.

This means that to recover from an incremental backup, you would need to restore the last full backup and then every individual incremental backup up to the most recent backup.

Advantages of differential backup

1. Faster recovery time: With differential backup, you only need the latest full backup and the most recent differential backup to restore your data. This offers a key advantage over incremental backups.
2. Efficient storage: Differential backups are smaller than full backups, reducing storage requirements compared to performing a full daily backup.
3. Improved data protection: Differential backups offer better data protection than incremental backups. If one incremental backup becomes corrupted, recovery can fail. With differential backup, only two files are needed for recovery – the latest full backup and the latest differential backup.
4. Simpler backup management: By having fewer restore points than incremental backups, differential backups make it easier for IT teams to manage and track their backup files.

Differential backup vs. incremental backup vs. full backup

There are advantages and disadvantages to each backup method. Deciding which option best suits your needs depends on how you choose to prioritise storage use, backup speed, and recovery time.

Differential backup offers a good balance between storage-heavy full backups and the slower recovery speeds of incremental backups. With only two files necessary, a differential backup provides a sensible middle ground.

When to use differential backup

Differential backup is suited to the needs of many different organisations:

• Large data sets: Businesses with large data sets that cannot afford to perform a full backup each day.
• Critical system management: IT teams that manage critical systems requiring regular backups without excessive storage costs.
• Efficiency savings: SMBs that need a strong backup strategy but without the complexity of incremental backups.

How to use differential backup

There are several best practices to follow when using differential backup:

• Schedule regular full backups: Performing full backups on a weekly or monthly basis helps to prevent differential backups from becoming too large.
• Use reliable backup software: Automated, cloud-based backup solutions allow you to manage differential backups with ease.
• Test your recovery process: Regularly verifying your backups will ensure they can be restored without errors.
• Monitor storage usage: Track differential backup sizes and adjust schedules if they grow too large.
• Secure backup data: Protect your backups from ransomware attacks by using offsite storage solutions.

Conclusion

Differential backup offers a balance between storage efficiency and fast recovery, making it a popular solution for many businesses and IT professionals. By only capturing the changes made since the latest full backup, differential backup reduces backup time and storage requirements while ensuring restoration remains swift.

Whichever method of data backup you choose, the most important thing is to ensure you have a strategy in place to protect you in the event of disruption.