The economics
of your situation may dictate that a decrease in performance in the event of a node
failure is more palatable than a larger initial outlay for more nodes or larger systems.
Protecting Against System Failure | 271
Much of the complexity of tuning and programming for scalability has been removed
since Oracle9i. Deployment was simplified in Oracle Database 10g when integrated
clusterware was first introduced. Interested readers can find more details about Real
Application Clusters scalability in the Oracle documentation and in Chapter 9 of this
book.
Node failure and Real Application Clusters
The database instances provide protection for each other??”if an instance fails, one of
the surviving instances will detect the failure and automatically initiate RAC recovery.
This type of recovery is different from the hardware failover discussed
previously. No actual ???failover??? occurs??”no disk takeover is required, since all nodes
already have access to the disks used for the database. There is no need to start an
Oracle instance on the surviving node or nodes, since Oracle is already running on
all the nodes.
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