Abstract
Purpose - The main objective of this paper is to study the optimal system for series systems with mixed standby (including cold standby, warm standby and hot standby) components. Design/methodology/approach - The paper deals with the reliability and availability characteristics of four different series system configurations. The failure time of the operative, hot standby and warm standby are assumed to be exponentially distributed with parameters l, l, and a respectively. The repair time distribution of each server is also exponentially distributed with parameter k. Findings - The mean time to failure, MTTFi, and the steady-state availability Ai(!) for four configurations are examined and comparisons made. For all four configurations, the configurations are ranked based on: MTTFi, Ai(!), and Ci/Bi where Bi is either MTTFi or Ai(!). Obviously, the system with height MTTFi and Ai(!), do not need frequent maintenance, i.e. less maintenance. Originality/value - Numerical results for the cost/benefit measure have been obtained for all configurations. It is interesting to note first that the optimal configuration using the cost/MTTFi measure is configuration 4. Next the optimal configuration using the cost/Ai(! ) measure is configuration 2.