Deleting Persistent Log Files
The device automatically saves logged system event messages in its storage memory, where they persist even if the device restarts or powers off. To make sure that the device doesn't store these logged files indefinitely, allowing personal information to always be available, it's recommended that you configure an "age" period for file rotation (i.e., creation of new file and deletion of oldest file).
If you configure an "age" period, the device creates a new file when either the configured file size is reached ('Persistent Log Size' parameter) or the "age" is reached ('Persistent Log Period' parameter), which ever occurs first. Therefore, even if the configured file size is not reached (even empty), when the period expires the device creates a new file, deleting the oldest persistent log file from storage.
For configuring persistent logging, see Configuring and Viewing Persistent Logging Storage.