Simulation of the model of computer mirroring based on difference queues

摘要

The paper describes modelling of the operation of a special case of two computer systems operating in parallel: computer mirroring. In computer mirroring one of the systems is identified as the main and the other as the backup computer, and bothcomputers execute the same tasks. Each system operates independently and is modelled as an execution unit processing a queue of tasks. The mirroring aspect of the system is modelled analytically with a difference queue. The analytical results are thenverified by simulating the behaviour of the parallel network of two queues, and measuring the resulting difference queue. The simulation results confirm the modelling of the behaviour of the d-queue as the standard M/M/l queue. Simulation results arecompared against theoretical estimates for number of tasks in the queue, in the system, mean time in the system, in the queue, for the main system, the backup system, and for the d-queue.