High data availability is crucial in every high performance environment. Even though network environments have improved a lot, costly data transfers remain the main drawback in achieving high performance in complex distributed applications which need to come up with additional design techniques to overcome this drawback. Continuing our previous research which focused on the design and implement...

Free Space Optics (FSO) is a telecommunications technology that transmits data in the form of optical signals across the air and, as such, can be considered as a wireless (line-of-sight) transmission system; this technology is capable of handling data rates at the Gbps level, does not require licensing, and can be deployed at one-fifth of the cost of fiber; also, the narrow beams employed in th...

With the advent of the smart grid, new challenges arise for electricity distribution. In particular, reliable power distribution will become evermore dependent upon information and communication technology (ICT). With this increasing dependency comes a need for a deeper understanding of the availability of those ICT components that maintain the power grid. This paper presents a study in which a...

Distributed systems are of unprecedented interest and importance today. Their omnipresence pervades many aspects of our daily lives leading to an increasing demand for dependability of such systems, sometimes very critically as in systems for air traffic control or public safety. As systems are expected to continue functioning even in the presence of failures, fault-tolerance as one means to en...

The instant system availability [Formula: see text] of a repairable system with the renewal equation was studied. The starting point monotonicity of [Formula: see text] was proved and the upper bound of [Formula: see text] is also derived. It was found that the interval of instant system availability monotonically decreases. In addition, we provide examples that validate the analytically derive...

This paper studies the availability equivalence of different designs of a repairable series-parallel system. Under the assumption that the system components have constant failure rates and repair rates, we derive the availability of the original and improved systems according to reduction, increase, hot duplication, warm duplication and cold duplication methods, respectively. The availability e...

The Domain Name System (DNS) provides a mapping between host names and Internet Protocol (IP) addresses. Hosts that are configured using the Dynamic Host Configuration Protocol (DHCP) can have their assigned IP addresses updated in a Dynamic DNS (DDNS). DNS and DDNS are critical components of the Internet. Most applications use host names rather than IP addresses, allowing the underlying operat...

The article describes the TSAR tool for system availability and availability analysis. Failure and repair model is based on Markov chain defined by states and transitions. Each state can be interpreted as working or broken. Transitions are defined by transition probabilities and transition time probability density functions. Availability and reliability analysis is based on discrete event Monte...

Standby techniques are used to improve system availability. Usually, a k-out-of-n:G standby system is assumed that when an operating component fails, a standby component becomes active and the system is working if at least k components are fault-free. In general, there are three types in component standby, i.e., cold, hot and warm standby. Cold standby implies that inactive components have a ze...

In this position paper we describe an important component of our overall approach to achieving high availability in the Coda file system. Coda, a descendant of the Andrew file system (AFS) [6], provides users with shared file access in a large-scale Unix1 workstation environment. Our goal is to provide users with the benefits of a shared data repository without the negative consequences of tota...