Reliability and availability cost design tradeoffs for HA systems

High availability (HA) has increasingly become an important feature for suppliers of computer network equipment to communication service providers and other organizations that run mission critical applications. The developing and operational cost of HA systems have also turned into one of the deciding factors in implementing HA systems, especially in the cost-sensitive business environment in recent years. This paper discusses the reliability and availability cost relationship and outlines key factors in HA engineering design. The manuscript comprises of five sections. Section 2 describes the general relationship between system availability and cost. Major issues of designing high available systems are addressed in Section 3. Section 4 briefly analyzes the overall availability performance of sample cluster systems, based on the actual performance data of the vendor X's top failure-prone single-node and dual-node cluster systems. It also breaks down the downtime by system and explores the correlation of availability and cost associated with cluster system hardware. Section 5 summarizes the cost factors to be considered for design tradeoffs analysis for enhancing the availability cost efficiency.