Organizations today are more aware than ever of how their business is exposed and can be immediately impacted by the interruption of access to critical applications and data. However, traditional data access solutions, tasked by many large organizations to provide near continuous uptime and access to data (also known as High Availability) often exceed ever-diminishing budgets due to their complexity and sophistication, and can leave small and medium-sized businesses (SMBs) in particular exposed to catastrophic outages and data loss.

This document will serve to outline High Availability in detail, focusing on its implementation and operation, and review the concepts of points of failure, multipathing, and load balancing, all integral components of the foundation of high availability. This paper will also discuss failover and failback mechanisms, and their relationship to a high availability environment. The discussion will include an analysis of how high availability, failover, and failback can be implemented in storage area networks (SANs) to provide continuous operation in the face of a wide variety of threats and potential disasters. To conclude, an outline of how high availability can be made more accessible to SMB users without terrific increases in cost and expense will be provided.