Modeling and optimizing periodically inspected software rejuvenation policy based on geometric sequences

• A periodically inspected rejuvenation policy for software systems is studied.
• A decreasing geometric sequence is used to denote the consecutive inspection intervals.
• The optimal inspection times and rejuvenation interval are found.
• The new policy is capable of reducing average cost and improving system availability.

Software aging is characterized by an increasing failure rate, progressive performance degradation and even a sudden crash in a long-running software system. Software rejuvenation is an effective method to counteract software aging. A periodically inspected rejuvenation policy for software systems is studied. The consecutive inspection intervals are assumed to be a decreasing geometric sequence, and upon the inspection times of software system and its failure features, software rejuvenation or system recovery is performed. The system availability function and cost rate function are obtained, and the optimal inspection time and rejuvenation interval are both derived to maximize system availability and minimize cost rate. Then, boundary conditions of the optimal rejuvenation policy are deduced. Finally, the numeric experiment result shows the effectiveness of the proposed policy. Further compared with the existing software rejuvenation policy, the new policy has higher system availability.