Most IT organizations provide services to the business in several forms. According to author Terry Critchley, services are comprised of three things:
Each of these things come together to ensure that required business functions are available. But every service has the potential for failure and outages even though today’s world demands that uptime be as close to 100 percent as possible. In this scenario, IT must use all of its technologies to provide this availability, including virtualization, cloud computing, disaster recovery, business continuity and strong security. Still, human factors can prevent services from being available, too.
For enterprise IT organizations that must provide reliable, redundant, secure and available services, the book “High Availability IT Services,” by Terry Critchley, will come in handy. The author discusses the types of architectures best for high availability such as clusters, grids and RAID storage. He also examines the importance of strong security practices when attempting to provide such services.
Critchley explains that IT must seriously consider all design aspects of the plan to provide highly available services—not just system infrastructure. Sure, hardware, vendors and software are an integral part of the plan, but so is the overall process and personnel that put the services into motion.
Other issues that are important when attempting to provide high availability services, according to the author, are the service level agreements (SLAs) and change management, which he also covers.
In our IT Downloads area, we offer a free download of an excerpt from this book, “Chapter 2: Reliability and Availability.” In this chapter, Critchley explains how people can have different interpretations of the terms reliability, availability and serviceability. He details different ways the terms can be used within the business, gives analogies for clarity, and then provides a quantitative approach to deciphering them. According to Critchley:
As we shall see, availability represents the probability that the system is capable of conducting its required function when it is called upon given that it has not failed or is undergoing a repair or an update action. Therefore, not only is availability a function of reliability, but it is also a function of the reparability, maintainability, or serviceability.
This book offers a detailed investigation of highly available services within today’s demanding enterprise business world. Any IT staff challenged with designing, implementing, deploying or providing highly available services in a large corporation would benefit from this information.