Real Application Clusters also deliver all the availability advantages that were a part
of OPS. Because all the machines in a Real Application Cluster share the same disk,
the failure of a single machine does not mean that the database as a whole has failed.
The users connected to the failed machine have to be failed over to another machine
in the cluster, but the database server itself will continue to operate.
As of Oracle Database 10g, the model implemented with RAC has been extended
beyond clusters to grid computing. Oracle now offers all the components you need
to use to implement clusters on several operating system platforms as part of the
Oracle software stack, including a volume manager and clusterware. In Oracle 10g
Release 2, Oracle made it possible to monitor the different nodes in a cluster and to
issue advisories to ensure better load balancing across the nodes.
High Availability
From an operational perspective, OLTP systems represent a company??™s electronic
central nervous system, so the databases that support these systems must be highly
available.
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