What is a Differential Backup? Your Guide to Data Protection

Created by On May 22, 2023 |  Last Updated On January 25, 2024
What is a Differential backup?

What is a Differential backup?

A Differential backup is a type of data backup will back up all the modified and new data since the last full backup. After a full backup, it provides the quickest restore method to recover an entire system.

If a full backup is run on a Friday, then a differential backup runs on Saturday; it will only back up the modified and new data since the full backup ran on Friday.

If the next backup that runs is on Wednesday and it is also a differential backup, it will back up all modified and new data since the Friday full backup. NOTE: It doesn’t just backup the modified data since the last differential backup that ran on Saturday.

How does a Differential backup differ from an incremental backup?

As the name suggests, an incremental backup will back up the modified and new data since the last backup. The previous backup can be a full, differential, or incremental backup.
A differential backup will back up all the new and modified data since the last Full backup.

History of Differential Backups

Differential backups were very popular when the world used tape drives for backup, mainly because you could run a full backup on a Friday and store the tape offsite.
Then for every day during the next week, you could use one tape for the daily differential backups and either leave it in the tape drive or remove it offsite each day.

If you had to restore any data, you only had to use two tapes (the last differential and full backup tapes). If a file that needed to be restored had been created since the previous full backup, you would only need the last full backup tape.

Are Differential Backups still used for online backups?

Our software will always run a full backup first. Incremental backups will run afterwards daily at 8 PM and retain the file history for five years.

Almost all IT Admins keep this setting except for changing the retention period.

When to use Differential Backups

Differential backups can be used when the following applies.

Efficiency: Differential backups upload only the modifications and new data since the previous full backup. This method can reduce restore times because only two backup sets (last full and differential) are required for a full restore.

Easier restores: When restoring data from a differential backup, you only need the last full and differential tapes. This is true even if your last full backup was two years ago.

Durable Data: Differential backups provide the same level of data durability as full and incremental backups.

How frequently should Differential backups be run?

The frequency of differential backups depends on your requirements, such as how often your data is modified. A popular setting is daily for most file types and is the same as incremental backups.

Conclusion

Differential backups can make your life easier when you restore data than incremental backups. Differential backups use more backup space, take longer to run and can be costly if you want to retain a long history of file retention.

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