Dell NetWorker 19.9 Administration Guide

Backup levels and data recovery requirements

The schedule and configuration of backup levels directly affects how long a recovery from a disk failure takes and how many backup volumes are needed for the recovery.

Plan the backup levels to minimize the number of volumes or the amount of disk space that is used to store the data. The fewer the number of volumes that are required to recover from a disk failure, the less the time that you require to restore the data.

The following example illustrates how the backup levels affect the requirements for data recovery.

In the following figure:

• Day 1—A full backup is run.
• Day 2— An incremental backup saves all files that have changed since the full backup.
• Day 3—Another incremental backup saves all files that have changed since Day 2.
• Day 4—A cumulative incremental backup saves all files that have changed since the full backup on Day 1.

To recover all data from a disk failure on Day 4, you need the data from the full backup from September 30 and the cumulative incremental backup on Day 4. You no longer need the data from Day 1, 2, and 3, because the volume with the cumulative incremental backup includes that information.