Difference Between Incremental and Differential Backup

The main difference between incremental and differential backup is that the incremental backup takes copies of changed data since the last backup while the differential backup takes copies of changed data since the last full backup.

When working with databases, it is important to keep a set of file backups. Taking backups is the process of taking copies of data. During a database failure, the data will be lost. Taking backups is useful in these kinds of situations. Full backup means to take copies of all the data or the files. Other backup making mechanisms are incremental backup and differential backup. Incremental backup takes the copy of data that has changed since the last backup. It can be a full back up or an incremental backup. On the other hand, a differential backup takes the copies of changed data since the latest full backup. Usually, incremental backup requires more restore time than a differential backup.

Key Areas Covered

1. What is Incremental Backup
    – Definition, Functionality
2. What is Differential Backup
     – Definition, Functionality
3. Difference Between Incremental and Differential Backup
     – Comparison of Key Differences

Key Terms

Differential Backup, Incremental Backup, Databases

What is Incremental Backup

Incremental backup takes the copies of data that has changed since the previous backup. An example scenario is as follows.

Assume that there was a full backup taken on Monday. On Tuesday, the incremental backup will take the changed files since Monday’s backup. On Wednesday, the incremental backup will take the changed files since Tuesday’s incremental backup. On Thursday, the incremental backup will take the changed files since Wednesday’s incremental backup. This process is continued until a full backup is performed again. On Thursday, if it is necessary to perform a recovery, it is necessary to consider the full back up on Monday and incremental backups on Tuesday, Wednesday, and Thursday.

The main advantage of incremental backup is that you only have to take backups of required data daily. On the other hand, during a recovery, it is necessary to consider the latest full backup and all the subsequent incremental backups. Therefore, it requires more restore time.

What is Differential Backup

A differential backup copies all the data that has changed since the last full backup. An example scenario is as follows.

Assume that there is a full back up taken on Monday. On Tuesday, a differential backup is taken on the changed data since Monday. On Wednesday, a differential backup is taken on all the changed data since Monday’s full back up. On Thursday, a differential backup is taken on all he changed data since Monday. This process continues until a full backup is taken again.

The main advantage of taking a differential backup is that you only need to consider the latest full backup and the latest differential backup during a recovery. On the other hand, the backups become progressively larger. As the same set of data is backed up, again and again, it contains more redundant data.

Difference Between Incremental and Differential Backup

Definition

An incremental backup is a backup in which successive copies of the data contain only the portion that has changed since the preceding backup copy was made. A differential backup is a type of data backup that preserves data, saving only the difference in the data since the last full backup.

Main Functionality

That is, the incremental backup takes copies of changed data since the last backup. The last backup can be a full backup, incremental backup, etc. The differential backup takes copies of changed data since the last full backup.

Redundancy

Furthermore, the differential Backup has more data redundancy than the incremental backup because the same copies of data are taken again and again.

Recovery

Moreover, the recovery is difficult in incremental backup as it takes time to rebuild data from the most recent full backup and each separate incremental backup. On the other hand, the recovery process is easier in differential backup as it only requires the latest full backup and the latest differential backup.

Restore Time

Also, the incremental backup takes higher restore time than the differential backup.

Conclusion

The difference between Incremental and Differential Backup is that the incremental backup takes copies of changed data since the last backup while the differential backup takes copies of changed data since the last full backup. Full backup refers to taking copies of all the data or the files.

Image Courtesy:

1. “Database symbol” (Public Domain) via Publicdomainfiles.com

Reference:

1. “What Is Incremental Backup? – Definition from WhatIs.com.” SearchDataBackup, Available here.
2. “What Is Differential Backup? – Definition from WhatIs.com.” SearchDataBackup, Available here.