Differences between a database differential backup and an incremental backup

For many beginners, it is difficult to understand the two concepts of differential and incremental backup, in this article we will explain the specific definitions and differences between incremental backups and differential backups:

　　Definition of differential backup:

Backs up data that has changed since the last full backup.

　　Definition of incremental backup:

Backs up data that has changed since the last backup, which contains a full, differential, incremental, backup.

By doing this, there is only a differential backup on the SQL Server 2000 database, and there is no incremental backup. Although we search for "incremental backup" in Books Online, there are two results.

　　Differences between incremental and differential backups:

There are generally three types of backups in Windows: full , differential, incremental.

　　Full backup:

Backs up all selected folders, and does not rely on the archive properties of the files to determine which files to back up. (During the backup process, any existing tags are cleared and each file is marked as backed up, in other words, the archive attribute is cleared).

　　Differential backup:

Differential backups are for full backups: All files that have changed since the last full backup was backed up. (During a differential backup, only those selected files and folders that are marked are backed up.) It does not clear the tag, either: After the backup is not marked as a backed up file, in other words, the archive attribute is not cleared.

　　Incremental backup:

Incremental backups are for the last backup, regardless of the backup: All files that have changed since the last backup were backed up. (During an incremental backup, only the marked selected files and folders are backed up, it clears the tag, either: Mark the file after the backup, in other words, clear the archive attribute.) ）

There are a few combinations of different backup types, as shown in the following example:

　　Full backup and differential backup:

A full backup was performed in Monday and a differential backup was performed from Tuesday to Friday. If the data is destroyed in Friday, then you only need to restore the Monday full backup and the Thursday differential backup. This strategy requires less time to back up the data, but less time to restore the data.

　　Full backup and Incremental backup:

A full backup was performed in Monday and an incremental backup from Tuesday to Friday. If the data is corrupted in Friday, then you need to restore the Monday normal backup and all incremental backups from Tuesday to Friday. This strategy takes less time to back up the data, but restores the data using more time