Breaking the Availability Barrier III: Active/Active Systems in Practice

Active/active architectures can extend failure times from years to centuries. Active/active systems comprise multiple independent nodes using a common distributed database cooperating in a common application. This book is the third volume of a three-part series on active/active systems. It gives real-life examples of existing active/active systems that are achieving such extraordinary failure intervals. As our daily lives and corporate well-being become more dependent upon computers, system reliability grows increasingly important. No longer are frequent system outages acceptable. Often, failure intervals must now be measured in centuries. In addition, the performance of these systems is analyzed; and a set of commercial off-the-shelf products are described that enable system implementations. There are many additional advantages of these multi-node architectures, such as unlimited scalability, load balancing, disaster tolerance, efficient use of all capacity, and risk-free failover testing. Also described are several other technologies related to high availability, such as the grid, virtual tape, and the Real Time Enterprise (RTE). There are many regulations being promulgated that require the use of high-availability computing. Many of these are summarized. Throughout this volume and the preceding two volumes, dozens of rules are formulated to achieve extreme availabilities. They are summarized here for handy reference.

Dr. Bill Highleyman, Paul J. Holenstein, and Dr. Bruce Holenstein have a combined experience of over 90 years in the implementation of fault-tolerant, highly available computing systems. This experience ranges from the early days of custom redundant systems to today's fault-tolerant offerings from HP (NonStop) and Stratus.Dr. Bill Highleyman has done extensive work on the effect of failure mode reduction on system availability. He has built fault-tolerant systems for train control, racetrack wagering, securities trading, message communication, and other applications. He is the Managing Editor of the Availability Digest (availabilitydigest.com).Paul J. Holenstein and Dr. Bruce Holenstein have architected and implemented the various data replication techniques required for the availability enhancements described in this book. Their company, Gravic, provides the Shadowbase line of data replication products to the fault-tolerant community.