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Oracle9i Data Guard Broker
Release 2 (9.2)

Part Number A96629-01
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4
Managing Database Resources

This chapter describes managing the states and properties that are specific to the database resource object in the following sections:

4.1 Database Resources

A database resource object is at the lowest level in the hierarchy of objects managed by the broker. A database resource object corresponds to a primary or standby database instance. The broker uses this object to manage and monitor the state of a single database.

The broker can distinguish between a physical and a logical standby database, and configures a physical standby site object and database resource object in a broker configuration, or a logical standby site and database resource object. These logical objects are configured with states, properties, and dependency relationships that are appropriate for their standby types.

4.2 Database Resource States

The state of a database resource is dependent upon the state of the site on which the resource resides. For example, if a site is in an offline state, the database that is dependent on the site must also be in an offline state.

When a site is in an online state and enabled, its database resource object can be in either an offline or an online state.

4.2.1 Offline State

When you first create and enable a configuration with the broker, the default state for database resources is online. Before setting the state to offline, you should carefully consider whether or not the interruption in access to data and the computing resources is necessary. The following list describes the actions the broker takes when you set a database resource to the offline state:

When you set the state of a primary or standby (logical or physical) database to offline, the broker automatically shuts down the database first and then restarts it (nomount).

4.2.2 Online State and Substates

When the broker first starts a database resource in the online state, the database resource is started in one of several substates. For example:

Table 4-1 describes all of the primary and standby database resource online states and substates. The first two columns of the table show the substate name if you are using Data Guard Manager and the corresponding name if you are using the CLI.

Table 4-1  Database Substate Names and Descriptions
Substate Name in CLI Substate Name in Data Guard Manager Description

LOGICAL-APPLY-READY

Apply Off

The logical standby database is open for read-only queries, but log apply services are not running. The logical standby database guard is on.

LOGICAL-APPLY-ON

Online

The logical standby database is open for read-only queries and log apply services are started. The logical standby database guard is on.

This is the default state for a logical standby database.

PHYSICAL-APPLY-READY

Apply Off

The physical standby database is mounted, but log apply services are stopped. The standby database is not open for read-only queries.

PHYSICAL-APPLY-ON

Online

The physical standby database is mounted and log apply services are started. The standby database is not open for read-only queries.

This is the default state for a physical standby database.

READ-ONLY

Read-only

The physical standby database is open for read-only queries, but log apply services are stopped. This substate is not applicable to logical standby databases.

READ-WRITE

Transport Off

The primary database is open for read/write access, but log transport services are not shipping logs to the standby databases.

READ-WRITE-XPTON

Online

The primary database is open for read/write access and log transport services are archiving redo logs to the standby databases.

This is the default state for a primary database.

4.2.3 Database State Transitions

Figure 4-1 graphically shows the online states and substates that were described in Table 4-1. The double arrows indicate that you can transition from one state to any other state.

Figure 4-1 Database State Transition Diagrams

Text description of transitn.gif follows.

Text description of the illustration transitn.gif

Figure 4-1 shows that the primary and standby databases can be in an offline state or, when online, can be in one of several substates:


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