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High Availability Overview

See Also:

Oracle9i Data Guard Concepts and Administration

Oracle9i Data Guard Broker

LogMiner Overview

LogMiner is a relational tool that lets administrators use SQL to read, analyze, and interpret log files. LogMiner can view both online and archived redo logs. The Enterprise Manager application LogMiner Viewer adds a GUI-based interface.

The ability of LogMiner to access data stored in redo logs helps you to perform many database management tasks. For example, you can do the following:

Track specific sets of changes based on transaction, user, table, time, and so on. You can determine who modified a database object and what the object data was before and after the modification. The ability to trace and audit database changes back to their source and undo the changes provides data security and control.

Pinpoint when an incorrect modification was introduced into the database. This lets you perform logical recovery at the application level instead of at the database level.

Provide supplemental information for tuning and capacity planning. You can also perform historical analysis to determine trends and data access patterns.

Retrieve critical information for debugging complex applications.

See Also:

Oracle9i Data Guard Concepts and Administration

Oracle9i Database Administrator’s Guide for more information about LogMiner

Real Application Clusters

Real Application Clusters are inherently high availability systems. Clusters typical of Real Application Clusters environments can provide continuous service for both planned and unplanned outages.

Real Application Clusters builds higher levels of availability on top of the standard Oracle features. All single instance high availability features, such as Fast-Start Recovery and online reorganizations, apply to Real Application Clusters as well.

Introduction to the Oracle Server 1-65

High Availability Overview

Fast-Start Recovery can greatly reduce mean time to recover (MTTR) with minimal effects on online application performance. Online reorganizations reduce the durations of planned downtimes. Many operations can be performed online while users update the underlying objects. Real Application Clusters preserves all these standard Oracle features.

In addition to all the regular Oracle features, Real Application Clusters exploits the redundancy provided by clustering to deliver availability with n-1 node failures in an n-node cluster. In other words, all users have access to all data as long as there is one available node in the cluster.

See Also: Oracle9i Real Application Clusters Concepts

Real Application Clusters Guard

Oracle Real Application Clusters Guard is an integral component of Real Application Clusters. Oracle Real Application Clusters Guard provides the following functions:

Automated, fast recovery and bounded recovery time from failures that stop the Oracle instance

Automatic capture of diagnostic data when certain types of failures occur

Enforced primary/secondary configuration. Clients connecting through Oracle Net Services are properly routed to the primary node even if connected to another node in the cluster

Elimination of delays that clients experience when reestablishing connections after a failure

A database server that runs Real Application Clusters consists of the Oracle database, Real Application Clusters software, and the Oracle Net listeners that accept client requests. These software components run on each node of a cluster. They use the services provided by the hardware, the operating system, and the port-specific Cluster Manager. The Cluster Manager monitors and reports the health of the nodes in the cluster and controls pack behavior.

See Also:

Oracle9i Real Application Clusters Concepts

Oracle9i Real Application Clusters Real Application Clusters Guard I - Concepts and Administration

1-66 Oracle9i Database Concepts

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