The NetVault Backup Log Daemon uses a default policy to delete obsolete logs, and accordingly deletes all system logs that are older than 30 days. You can override this behavior with one of the following types of user-defined policies:
From the left navigation pane, select Change Settings, and then click the Logging Daemon icon.

Age-based Purge Policy – For a purge policy based on the log age, configure the following parameters:
Page-based Purge Policy – For a purge policy based on the page size, configure the following parameters: