RAC coordinates traffic
among the systems or nodes, allowing the instances to function as a single database.
As a result, the database has proven to scale across dozens of nodes. Since the cluster
provides a means by which multiple instances can access the same data, the failure of
a single instance will not cause extensive delays while the system recovers. You can
simply redirect users to another instance that??™s still operating. Applications can leverage
the Oracle Call Interface (OCI) to provide failover to a second instance transparently
to the user.
Database Security Features | 27
Data Guard and RAC
Data Guard and RAC in combination replaced Parallel Fail Safe beginning with
Oracle9i. Data Guard provides automated failover with bounded recovery time in
conjunction with Oracle Real Application Clusters. In addition, it provides client
rerouting from the failed instance to the instance that is available with fast reconnect
and automatically captures diagnostic data.
Automated Storage Management
Oracle Database 10g introduced Automated Storage Management (ASM), which
provides optimum striping and mirroring of data for performance and availability.
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