The difference between full, incremental and differential backup

A common question regarding backup schemes and practices is “What’s the difference between full, incremental and differential backup”?

While it’s possible to protect your data using all these backup types, they bring pros and cons you need to consider before adopting them.

Starting from the principles, a solid backup scheme should:

  • copy your important data to different backup destinations;
  • allow you to restore previous versions of the backed up files (data retention policies);
  • be a good trade-off between security and storage space occupation.

Considering these three fundamentals, let’s see how full, incremental and differential backup work:

  • Full Backup: it’s a complete copy of the data, without any exclusion. As simple as it sounds.
  • Incremental Backup: it’s a copy of the data created and modified since the last backup performed (both full and incremental). The backup will occupy less space but you will need the latest full backup and all the incremental backups – performed after the latest full – in order to restore the data.
  • Differential Backup: it’s a copy of the data created and modified since the last full backup performed. The backup will occupy more space than the incremental mode but you will only need the latest differential backup and the latest full backup in order to restore the data.

What type of backup should I use?

That’s usually the second question and the answer is simple and complex at the same time: it depends on your needs.

Full backups are solid but costly. I suggest to use them with files and folders rarely updated, so you can enact relaxed data retention policies and save disk space.

Differential backups are a good trade-off in many scenarios, but don’t be too strict with backup retention.

Incremental backups are more efficient, a common scheme is to perform a full backup per week and daily incremental backups. They are excellent when you enforce strong data retention policies.

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