Chapter 1. High Availability

High availability is a discipline within database technology that provides a solution to protect against data loss and against downtime, which is costly to mission-critical database systems. In this chapter, we will discuss how Oracle 11g RAC provides you with mission-critical options for minimizing outages and downtime as well as how RAC fits into the overall scheme for maintenance of a comprehensive disaster recovery and business continuity policy. In this chapter, we will provide you with an introduction to the high availability concepts and solutions that are workable for Oracle 11g. As such, we will provide details on what constitutes high availability and what does not. By having the proper framework, you will understand how to leverage Oracle RAC and auxiliary technologies including Oracle Data Guard to maximize the Return On Investment (ROI) for your data center environment. In summary, we will discuss the following topics:

• High availability concepts

• Fault-tolerant systems and high availability

• High availability solutions for Oracle 11g R1 and 11g R2 Real Application Clusters (RAC)