Fundamentals: Retention Periods

There are various kinds of retention periods that Bacula recognizes. The most important are File Retention Period, Job Retention Period, and the Volume Retention Period. Each of these retention periods applies to the time that specific records will be kept in the Catalog database. This should not be confused with the time that the data saved to a Volume is valid and available for restore – in many cases, data will be available much longer than any of the Retention Periods configured (the data remains in the Volume until the Volume is recycled or truncated).

More details about Schedules and Retentions.

File Retention Period

File Retention Period determines the time that File records are kept in the Catalog database. This period is important. As long as File records remain in the database, you can “browse” the database with a Console program and restore any individual file. Once the files are removed or pruned from the database, these files associated with a backup job can no longer be browsed. File records of a Volume use the most space in the database. As a consequence, you must ensure that regular pruning of the file records is done to keep your database from growing too large.

See the Console prune command for more details on this subject.

Job Retention Period

Job Retention Period is the length of time that Job records will be kept in the database. Note that Files records are associated to a job. File Records can also be purged disassociating themselves from a job. In this case, information will be available about the Jobs that ran, but not the details of the files that were backed up. Normally, when a job record is purged, all of its associated file records will also be purged.

Volume Retention Period

Volume Retention Period is the length of time between the last write and the volume’s re-usage moment. Simply, it’s the period of the files being stored. Bacula will normally never overwrite a Volume that contains the only backup copy of a file. As for the Catalog, it retains information for all files backed up for all current Volumes. Once the Volume is overwritten, data from the Catalog is removed as well. Thus, if there is a very large Pool of Volumes or a Volume is never overwritten, the Catalog database may become enormous. Bacula will normally not overwrite a Volume that contains data still inside its Retention period, but select a Volume which is out of its Retention time for recycling.