This property works with the DiscardTimeUnit property and indicates a time interval in which alarm data is stored on a database table, until it is discarded. Default value of this property is 1 (one time unit indicated by the DiscardTimeUnit property). If this property is configured with a value less than or equal to the BackupDiscardInterval property, E3 automatically sets the value of BackupDiscardInterval as doubles the value of DiscardInterval.