Dependable IT system building technologies

With the increasing utilization of IT systems, due to the availability of broadband services and popularization of mobile phones, the influences of malfunctions are becoming greater as well. The concept of high availability is essential for building IT systems that make it possible to use the desired services whenever they are wanted and at the expected service levels, which are dependable IT systems. The causes of failures are diverse, ranging from the deterioration of hardware with age to malfunctions of complex and varied software, such as operating systems and middleware. Appropriate building technologies are necessary to realize IT systems that will not interrupt services when either scheduled or unexpected shut downs take place, while minimizing service down time. IT system building technologies with the assumption of failsafe systems are summarized in this paper.