6 Data Guard Monitor

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When you use the Data Guard GUI or the CLI to manage a database, the DMON

process is the server-side component that interacts with the local database and the

DMON processes of the other databases to perform the requested function. The

DMON process is also responsible for monitoring the health of the broker

configuration and for ensuring that every database has a consistent description of

the configuration.

See Also: Oracle Database Concepts for more information about the



memory structures and processes that are used with an Oracle

database

Figure 1–4 shows the broker’s DMON process as one of several background

processes that constitute an instance of the Oracle database. Figure 1–4 shows

multiple databases, each having its own DMON process. This distributes the broker

across all of the databases of the broker configuration.



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Figure 1–4 Databases With Distributed Broker (DMON) Processes



User



User



User



User

Processes



User



Oracle Database Instance



Recoverer

(RECO)



Process

Monitor

(PMON)



System

Monitor

(SMON)



Data Guard Database

Monitor

Writer

(DMON)

(DBW0)



Log

Writer

(LGWR)



Archiver

(ARC0)



Oracle

Background

Processes



Primary Database

Standby Database

Recoverer

(RECO)



Process

Monitor

(PMON)



System

Monitor

(SMON)



Data Guard Database

Writer

Monitor

(DBW0)

(DMON)



Log

Writer

(LGWR)



Archiver

(ARC0)

Oracle

Background

Processes



Oracle Database Instance



User



User



User



User



User

Processes



The zigzag arrow in the center of Figure 1–4 represents the two-way Oracle Net

Services communication channel that exists between the DMON processes of two

databases in the same broker configuration.

This two-way communication channel is used to pass requests between databases

and to monitor the health of all of the databases in the broker configuration.

When creating a new Data Guard configuration or adding a new standby database

into an existing configuration, the DMON process uses an initial connect identifier



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to connect to the database to collect necessary information about the database. This

initial connect identifier is supplied by the user if the CLI is used, or constructed

automatically if the GUI is used.

After the initial connection, the DMON process constructs connect descriptors for

communication with other DMON processes on other databases, using the address

value from the LOCAL_LISTENER initialization parameter from those databases.

The DMON processes automatically manage the connections to each other. If a

database is a RAC database, then as long as one instance in the database is running

and the DMON process is started on the instance, that DMON process is able to

establish two-way communications with other DMON processes on other databases

to manage the database as part of the Data Guard configuration.



1.6.2 Configuration Management

The broker’s DMON process persistently maintains profiles about all database

objects in the broker configuration in a binary configuration file. A copy of this file

is maintained by the DMON process for each of the databases that belong to the

broker configuration. Each database’s copy of the file is shared by all instances of

the database if it is a RAC database. Changes to this file are made by the DMON

process for all copies.

This configuration file contains profiles that describe the states and properties of the

databases in the configuration. For example, the file records the databases that are

part of the configuration, the roles and properties of each of the databases, and the

state of each database in the configuration.

The configuration data is managed transparently by the DMON process to ensure

that the configuration information is kept consistent across all of the databases. The

broker uses the data in the configuration file to configure and start the databases,

control each database’s behavior, and provide information to the CLI and the Data

Guard GUI. (See Section 3.3 for more information.)

Whenever you add databases to a broker configuration, or make a change to an

existing database’s properties, each DMON process records the new information in

its copy of the configuration file.



1.6.3 Database Property Management

Associated with each database are various properties that the DMON process uses

to control the database’s behavior. The properties are recorded in the configuration

file as a part of the database’s object profile that is stored there. Many database



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properties are used to control database initialization parameters related to the Data

Guard environment.

To ensure that the broker can update the values of parameters in both the database

itself and in the configuration file, you must use a server parameter file to control

static and dynamic initialization parameters. The use of a server parameter file

gives the broker a mechanism that allows it to reconcile property values selected by

the database administrator (DBA) when using the broker with any related

initialization parameter values recorded in the server parameter file.

When you set values for database properties in the broker configuration, the broker

records the change in the configuration file and propagates the change to all of the

databases in the Data Guard configuration.

Note: The broker supports both the default and nondefault server



parameter file filenames. If you use a nondefault server parameter

filename, the initialization parameter file must include the complete

filename and location of the server parameter file. If this is a RAC

database, there must be one nondefault server parameter file for all

instances.



See Also:



Section 3.3.2 for more information.



1.7 Oracle Data Guard Installation, Upgrade, Downgrade, and First Use

Oracle Data Guard, the Data Guard monitor, and the Data Guard command-line

interface (DGMGRL) are included with the Enterprise Edition or Personal Edition of

the Oracle database software.

The Data Guard graphical user interface (GUI) is included with the Oracle

Enterprise Manager software.

Note: In Oracle9i, the Data Guard GUI was called Data Guard

Manager and was usable either through the Oracle Enterprise

Manager Console or by invoking it directly from the command line.

In Oracle Database 10g, it is tightly integrated with Oracle

Enterprise Manager and is referred to as the Data Guard GUI.



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1.7.1 Installation

To use the Data Guard monitor and the CLI, you must install the Oracle Enterprise

Edition or Personal Edition database on each location where you plan to manage

broker configurations.

The Oracle Data Guard graphical user interface (GUI), which you can use to

manage broker configurations, is installed with the Oracle Enterprise Manager

software.



1.7.2 Upgrade from Release 9.0.n to Release 10.1

If you are currently running an Oracle Data Guard release 9.0.n configuration, you

must upgrade to Oracle Database release 10.1 and re-create the broker

configuration, as follows:

1.



Delete (remove) the release 9.0.n broker configuration using the same release of

either Data Guard Manager or the CLI. For example, the CLI REMOVE

CONFIGURATION command can be used.



2.



Upgrade the database software to Oracle Database release 10.1. See the Oracle

installation documentation that is appropriate for your operating system.



3.



If you are using Oracle Enterprise Manager and Data Guard Manager release

9.0.n, you must upgrade to Oracle Enterprise Manager release 10.1 to manage a

broker configuration running Oracle Data Guard release 10.1:

I



I



4.



Data Guard Manager release 9.0.n is not compatible with Oracle Data

Guard release 10.1.

Data Guard GUI release 10.1 is not compatible with Oracle Data Guard

release 9.0.n. You will receive an error message stating that the Oracle

database is too old.



If you are using the CLI release 9.0.n, you must upgrade to Data Guard

command-line interface release 10.1:

I



The CLI release 9.0.n is not compatible with Oracle Data Guard release 10.1.

Note: Existing Oracle9i command-line scripts are supported in



Oracle Database 10g for non-RAC databases. See Appendix A for

information about deprecated commands.

I



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Oracle Data Guard Broker