Incremental and Differential Backup

August 6, 2019

These two options of incremental and differential backup are two advanced backup methods that can help to reduce backup time and storage space.

General Introduction

With more image files created, there will be more and more data and files stored on your system drive, data partitions, etc. In order to ensure data integrity and make full use of your disk space, it is important to back up changed data regularly.Once you have created an backup task, you will see this task under Backup Management. Click "Backup" option, you will see three options: Full Backup, Incremental Backup and Differential Backup. The following paragraphs describe the differences among them and can help you select which backup plan you want to use:

Home Incremental Differential

Tips: For detailed info about how to perform an Incremental or Differential backup, please refer to: How to Do Incremental and Differential Backup.

What's the Difference among Full Backup, Incremental and Differential Backup?

Full Backup

A full back up takes a snapshot of all the data on the selected folders, partitions or hard disks at the time the backup is performed and saves it to an image file. A full backup is always the basis of any incremental and differential backup. A Full Backup can be used to restore all the files and folders from its image to the state when the image was created. Once you have performed a Full backup, you can create Incremental and Differential backups. These are much quicker to create than a Full backup of the same data and the images created are smaller.

Incremental Backup

An Incremental backup takes a snapshot only of the changed and newly added files based on the previous related backup, it would be a full or incremental backup. Data that have not changed will not be backed up. Thus, the time and image storage space required for incremental backup are both less than a full backup. A Full Backup must exist as the start point of a series of incremental backups. A typical set would be in time sequence. All the image files of incremental backup series share a sequential relationship and data can be recovered to the state when any Incremental Backup was done. If any one of the incremental image files in the sequence is damaged or missing, then subsequent image files will be invalid.

Differential Backup

A Differential Backup is always directly related to its originating Full Backup. It will back up all data added and changed since the Full backup was done. Therefore, compared to a full backup, the backup time and image file storage space required are both less. If one of the differential backup image files becomes damaged or lost, it will not affect others. All data can be returned to the state when the Differential Backup was done and you can select the one created that you want to recover to perform restore. Once data added and changed a lot, then each Differential Backup will become progressively larger, because each one will contain more changes made since the last Full Backup was done. Compared to Incremental back up, Differential Backup costs more time and requires more disk space.

Differences among Full, Differential and Incremental Backup

The differences mainly lie on the backup source, backup time, image storage, and restore speed. Here is a table listing these items.

Differences among there backups.png

Which to Choose, Full, Differential or Incremental?

Full Backup + Incremental or Differential

With the demonstrations above, you might have found out that the method of "Full Backup + Incremental Backup" or "Full Backup + Differential Backup" will be more convenient than a single full backup. Therefore, after performing a full backup, you can choose whether incremental or differential backup to deal with the changed and newly added data and files. What's more, the way of "Full Backup +Incremental Backup" has been employed more frequently than other approaches as it only deals with the changed files since the last incremental backup. Therefore, if you need to back up data regularly, this way will be more popular and time-saving. The way of "Full Backup + Differential Backup" is also a good solution,however, compared to incremental backup, it will cost more time and also it needs more space to store the image file.


  • If anyone of the incremental image files in the sequence is damaged or missing, then subsequent image files will be invalid.

  • A Full Backup must exist as the start point of a series of incremental backups or differential backups.

  • If you have not created any backup task and you want to create an incremental backup or a differential backup, then you need to create a new backup task first and Aomei Backupper will run it as a full backup by default for the first time.