Incremental Backups

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Overview

For the DB2, DB2 DPF, Informix, Oracle, Oracle RAC and SAP iDataAgents, Incremental backup works as described in differential backups. See Differential Backups for information on Incremental backups for these iDataAgents.
Incremental backups behave differently on Notes Database and Notes Document clients. See Incremental Backups - Lotus Notes for more information.
For the DB2 and DB2 DPF iDataAgents, Delta backup works as described below.

An incremental backup contains only data that is new or has changed since the last backup, regardless of the type. On average, incremental backups consume far less media and place less of a burden on resources than full backups.

The following illustration clarifies the nature of full and incremental backups. For simplicity, assume there is a file system that contains six files as represented in the figure.

Note that the File System above could also represent database tables, Active Directory objects and attributes, etc.

Backup #1 is a full backup and therefore writes all the data, changed and unchanged, to the backup media. Backups #2 through #n-1 are incrementals and only back up those files that have changed since the time of the last backup, regardless of the type. For example, files A, B, and E changed after the full backup and were therefore backed up in Backup #2. Backup #4 backed up files A and D because both files were modified sometime after Backup #3 occurred. File F did not change; hence, it was not backed up in any of the incremental backups, but it was included in both full backups, which, by definition, back up everything.

See Backup Data for an overview of all backup operations.

For Windows File System iDataAgent, if you are using Change Journal or Data Classification as the scan method, the incremental backup will backup all the new or changed data since the last incremental or full backup, ignoring any differential backups performed prior to the current backup.
For the NetWare iDataAgent, any data that was backed up with a differential backup will be backed up again when performing a subsequent incremental backup.