1536: Difference between Full, Incremental and Differential Backup

In what way full, differential and incremental backups differ from each other


An incremental backup contains all changes that have been made since the latest incremental or full backup was created. If one full backup and several incremental were created, all of these backups must be saved in the same folder so that you will be able to restore the data. If one of incremental backups or a full backup is deleted, there is no way to restore the set, since all backups are dependent on each other.

A differential backup contains all changes that have been made after the full backup creation. To restore a differential backup, Acronis backup software must match the differential backup with the original full backup.

So, If your objective is to reduce backup size and backup time, then the best strategy would be to create incremental backups. On the other hand, if you want to increase backup reliability, by not having to rely on a chain of incremental backups, then differential backups would be the best solution.

Here is a graphical representation of the differences between full, incremental and differential backups:

Click the picture to enlarge

More information

An incremental or differential backup created after the disk is defragmented might be considerably larger than usual. This is because the defragmentation program changes file locations on the disk and backups reflect these changes. Therefore, it is recommended that you re-create a full backup after disk defragmentation.

Technically there is no limit on the number of incremental/differential backups in a chain. However, since one invalid incremental backup makes all consequent incremental backups inaccessible, it is recommended to create a  new full backup after several incrementals and start a new chain.

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