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Oracle Parallel Processing by Sanjay Mishra, Tushar Mahapatra

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Planning for Failover with OPS

When a failover occurs in an OPS environment, the workload of the node that failed is redirected to one or more designated backup OPS nodes. When you’re planning for failover in such an environment, you have to consider the impact of failover on the performance of the designated backup nodes and also on application partitioning. A new Oracle8i OPS feature we describe in this section can be used to designate one of the nodes as a primary instance and the other as a secondary instance where OPS is exclusively used for failover purpose.

Capacity and Workload Issues

After a failover, the applications that were running on the failed instance will be running on one or more of the surviving instances. OPS instances must be able to accommodate this additional workload. You need to design your OPS environment so that any instances that you plan to use for failover purposes have enough extra memory and CPU resources to handle the additional workload that results when a failover occurs. Otherwise, a failover might result in a performance bottleneck. Another approach to this issue is to design your applications so that the workload on nodes designated as failover nodes is reduced when a failover occurs. You could, for example, stop nonessential reports from running in order to free up resources for mission-critical transaction systems.

Redistributing applications in an OPS environment during a failover has implications for application partitioning. After the workload ...

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