We receive a number of questions about which backup type to choose: an incremental or a differential backup. The answer is - it depends. In this article, we will review the difference between an incremental and a differential backup and provide advice on the usage of both.
Incremental and Differential Backup Definitions
An incremental backup is a type of backup that uploads changed and modified files or parts of files compared to the latest backup set.
An incremental backup is typically used for the backup of files, full system images, applications’ data, and databases. It’s quite popular and is commonly offered by backup software developers.
A differential backup is a type of backup that uploads changed and modified files or parts of files compared to the initial full backup. It is typically used for the backup of Microsoft SQL Databases. For other backup datasets, backup software developers do not use differential backups.
Incremental and Differential Backups Compared
Incremental and differential backup types both perform the backup of changed and modified files. However, there is a distinct difference between the two.
- A differential backup grows over time as it consists of all changes since the initial full backup. Thus, it’s slower and takes more storage space than an incremental backup.
- During a recovery, incremental backup software needs to process each increment change and the first full backup to restore data to the required state. This process is slower compared to recovery from a differential backup.
- In an incremental backup, each next increment change relies on the previous one. This means if any of the changes are lost, the whole dataset is lost. To recover from the differential backup, you only need two “files” - the initial full backup and the latest differential.
- Since incremental backups are typically smaller, they can run more often and more data is preserved in the event of a disaster. Incremental backups allow better RPO.
Nowadays, a differential backup is not used for other datasets and cannot be enabled in most backup software solutions. You will encounter a differential backup while working with Microsoft SQL Server Backup. If you want to know more - check out our article about a differential backup.
The incremental backup has become the most common type used to back up various files and datasets. By default, most backup software developers implement an incremental backup. If you want to know more about using an incremental backup, check out our article.
Incremental and differential backups have different use cases and are used for different data-sets. Your backup software is most probably set to run incremental backups forever if you are performing a backup of files or system images. However, if you are running a backup of SQL databases, you would definitely encounter the differential backup.