I would not call it a wierd truncation, but consider that data conversion usually sets the time component to midnight. Therefore, your 11-30-01 becomes 11-30-01 00:00:00. If you have data that was done later that day, say a 2pm, it would have a time of 11-30-01 14:00:00 and not qualify for the partition without an overflow partition there would be no place to put it.