Universal Redundancy Software Design And Implementation For Combination System Based On Fault Tree And Priority

The high availability (HA) is an essential requirement of the system in the field of military affairs, medical service, finance and communication. Besides recovering data from backup, customer also requires twenty-four seven service. That's to say the system reliability should be above 99.999%. To reach this target, we have to equip the spare hardware and employ the controlling software at the same time.The topology of system can be transformed into combination system of series and parallel. This paper introduces a universal redundancy software design for combination system based on fault tree and priority. Once the state of unit is changed, the redundancy software will update the node's priority along its fault tree and reassign the active/standby role by the priority's comparison. An event at the same time will be broadcast to trigger all observers'private processing in time.The core of this solution lies in sharing same priority scheduling with different fault tree topology. Dividing commonness from individuality will benefit us by decreasing maintenance and updating cost, which is consistent with refactoring principle in software engineering.