Although these
initialization parameters exist in any instance, in a single-instance environment they are either
null or have a value of 1 (for example, INSTANCE_NUMBER). In Table 10-3, I give you an
overview of some of the key RAC-related initialization parameters.
Dynamic Performance Views
In a single-instance environment, all dynamic performance views that begin with V$ have a
corresponding view beginning with GV$, with the additional column INST_ID always set to 1. For a
RAC environment with two nodes, the GV$ views have twice as many rows as the corresponding
V$ views; for a three-node RAC, there are three times as many rows, and so forth. In the sections
that follow, we??™ll review some of the V$ dynamic performance views that show the same contents
regardless of the node you are connected to, along with some of the GV$ views that can show
you the contents of the V$ views on each node without connecting to each node explicitly.
Initialization Parameter Description
INSTANCE_NUMBER Unique number identifying this instance in the
cluster.
INSTANCE_NAME The unique name of this instance within the
cluster; typically the cluster name with a numeric
suffix.
CLUSTER_DATABASE This parameter is TRUE if this instance is
participating in a RAC environment.
CLUSTER_DATABASE_INSTANCES The number of instances configured for this
cluster, whether each instance is active or not.
ACTIVE_INSTANCE_COUNT Specifies the primary instance in a two-node
cluster; otherwise, it is the number of instances
in the cluster.
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