• The point of confusion here may be the recovery model set to "Full". When the recovery model is set to full, that means you are taking full backups, (Probably differential backups), and -here's the important part- regular log backups. These are *required* for the Full recovery model.

    If you use the "Simple" recovery model, you are indicating to SQL server that you will be taking full backups from time to time.

    In simple recovery mode, when you take a full backup, I believe the log file is backed up and truncated.