The default retention option keeps a certain number of full backups and any associated dependent (incremental or differential) backups. Each new full backup begins a new "Backup Cycle".
Time-based retention is also available. Please see How can I keep backups for a specific amount of time? below.
ZCB will track how many successful full backups have been performed for a given backup set. When a new full backup completes, any excess full backups and their dependents will be removed within 24 hours. T
The number of full backups to retain is configurable, with no upper limit. Special retention values for "forever" and "delete after upload" are also available.
The user has chosen to retain 2 full backups.
By default, backups are purged once per day, at midnight. This time is configurable from the Advanced menu under Preferences.
Incremental and Differential backups are "dependent" upon a Full backup. When a full backup is purged, any dependent Incremental or Differential backups will be purged at the same time.
The ability to retain backups "forever" still exists. Change the number of full backups to retain to zero. Please note that this will have a significant effect on total storage space used over time, because any backup with a retention of "forever" will not be removed.
The ability to "delete after upload" exists for local backups. Change the number of cycles to retain to -1.
The ability to retain backups for a given amount of time exists. Click the Edit button in the Retention settings section. Then choose Time Retained instead of Number of Cycles.
New options will appear. Backups can be retained for any number of days, weeks, months, years. Special retention values of "forever" and "delete after upload" are also available.