10.1 Introduction

In the previous chapter we browsed through definitions of the various data dictionary views and parameters pertaining to RAC. All dynamic views that are available in a single stand-alone configuration of Oracle are available from a global level. What this means is that these global views will provide visibility to all instances participating in the clustered configuration. DBAs could view the statistics of any instance from any other instance in the cluster. For example, to look at the users connected to instance RAC2 from instance RAC1, the global view GV$SESSION could be queried where the INST_ID has a value of 2, or by querying the entire view information from all views.

Oracle has introduced and maintains several initialization parameters that are specific to a RAC configuration. The previous chapter also discussed these parameter definitions. The usage of many of the parameters is covered later in the appropriate chapters of this book.

Availability of a football player of 94% indicates that the player has missed one game of a 16-game season. However, 99.97% availability of a computer system indicates a downtime of 2.5 hours in a year. Today's business requirements are to meet 99.99% or 99.999% availability, which indicates 0.5 hours or no downtime. To meet these high-availability requirements with no downtime in a year, the factor critical for success is for systems to provide automatic failover when one participating system fails, with minimal interruption to the user. If this does not occur, when a system...