NetWorker: How Save Set Retention and Dependencies Work

Summary: This KB provides a general overview of how NetWorker save set retention works in regards to backup levels and dependencies.

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Instructions

Typical weekly backup: Full once a week, incr the rest of the week.

Backups retained for 6 weeks

7 days in a week * 6 weeks retention

6*7 = 42 days
 
SUN MON TUES WED THRUS FRI SAT
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR
FULL INCR INCR INCR INCR INCR INCR


UNDERSTANDING NETWORKER DEPENDENCY TRACKING:
 
  • NetWorker performs save set dependency tracking.
  • Dependency tracking ensures that dependent save sets are retained even if retention has expired.
  • Data is not purged until both of the following are applicable:
    • The backup data is outside its specified retention time.
    • All other backups that depend on the data are also outside their retention time.
  • When there is a mix of full and incr; or full, incr, and differential backups, this becomes important.

DEPENDENCY CHAINS:
 
  • The dependency chain is a sequence of backups where each backup depends on a previous backup in the chain.
  • An incremental done after full depends on the full.
  • The next incremental depends on the incremental before it (which in turn depends on the full before it).


WHAT DEPDNDENCY TRACKING MEANS:
 
  • In the below scenario, a sequence of backups is performed with 6-week retention.
  • In this scenario, the FULL backup is outside the retention period; however, the incr backups which depend on the full backup are inside the retention period.
  • NetWorker will not delete the FULL Backup until its dependents have reached their retention period.
  • Once the final dependent save set's retention is expired, the entire chain is marked for expiration and deleted.
WHAT HAPPENS IF A FULL BACKUP FAILS:---
 
  • In the following scenario, the scheduled full backup failed and there was no rerun.


 
  • The next scheduled incr backup follows the chain from the previous full backup and its subsequent incrementals. This extends the retention of the previous chain until a new full is performed.
  • Once a new full is performed the previous chain reaches expiration as per the retention date on the final save set.

Affected Products

NetWorker Family, Backup and Recovery Manager NetWorker, NetWorker
Article Properties
Article Number: 000197019
Article Type: How To
Last Modified: 06 Aug 2025
Version:  5
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