On-duty mode is usually used in occasions that require high real-time performance of the system, such as telecommunications, medical care, transportation, energy and other fields. In these fields, if the system fails or stops running, it will have a great impact on society, economy and people's lives. Therefore, in order to ensure the reliability and real-time performance of the system, it is necessary for personnel to continuously supervise and maintain the operation of the equipment.
The disadvantage of duty mode is high cost and needs continuous personnel supervision and maintenance.