Reference Topics
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B
Incremental Backups
NetBackup supports two types of incremental backups:
• Differential: backs up only the data that has changed since the last full or
differential incremental.
• Cumulative: Backs up all the data that has changed since the last full
backup.
The next two topics compare the relative retention requirements and the
backup and restore times of these two types of incremental backups. The third
topic in this section explains how NetBackup determines the files to include in
an incremental backup.
Retention Requirements
The following table compares the retention requirements for differential- and
cumulative-incremental backups.
Type
Retention
Requirement
Comments
Differential
longer
It is necessary to have the last full backup and
all the differential incrementals that have
occurred since the last full backup in order to
ensure that all files can be restored. Therefore,
all the differentials must be kept until the next
full backup occurs.
Cumulative
shorter
Each cumulative-incremental backup contains
all the changes that have occurred since the last
full backup. Therefore, a complete restore
requires only the most recent cumulative
incremental in addition to the full backup.
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT