Data Guard Broker Tips
Oracle Tips by Burleson Consulting
December 3, 2011
Data Guard Broker
Data Guard Broker is an assistance utility that
is provided with Oracle Database Server software to facilitate the
creation and management of Data Guard configurations. Data Guard
Broker consists of server side and client side components that are
used together in the implementation of a distributed computing
The server side component includes a Data Guard
Monitor (DMON) process and configuration files. The client side
component includes Data Guard Manager and a Command Line interface.
Data Guard Broker manages a Data Guard
configuration using a broker management model. The broker management
model is a hierarchal structure comprised of Configuration, Site and
Database resources. Broker can manage all three layers of the
management model. More information about the broker management model
will be presented later in this section.
Data Guard Broker is available with Oracle 9i
Release 2 or above.
Data Guard Broker
Data Guard Broker can manage the primary
database and up to nine standby databases in one configuration.
These nine standby databases can be a mixture of physical and
logical standby databases. Standby databases can be created using
Data Guard broker. In addition, it can be used to add an existing
Data Guard primary database to a configuration.
When a Oracle instance
is created using
Broker, Broker takes care of the entire set of supporting files such
as SPFILE, Oracle Net configuration files, etc. If a DBA needs to
add an existing Oracle instance
to a Data Guard configuration, the
SPFILE and Oracle Net files must be configured manually before the
Data Guard primary database is added to a configuration. If Data Guard Broker
is to be used for the management of standby databases, SPFILE must
be used to hold the initialization parameters on all the
Some advantages of using Data Guard Broker are
It is a centralized management tool that can be
used to manage the entire configuration using a GUI or CLI
It provides an extensive health check mechanism
for the primary database, standby databases and supporting services
in the configuration.
It reduces the complexity of role management
services. Switchover and Failover operations can be performed from a
It can be used to gather useful statistics for
fine tuning the log transfer and log apply services.
In Oracle 9i and beyond, Data Guard Broker cannot be used
with Oracle Real Application Cluster. RAC support is provided with
Oracle 10g and beyond.
The following subsections will present the
broker management model and the broker components, in brief.
Data Guard Broker Configuration, Data Guard
Broker Sites and Data Guard Broker Resources
The Broker management model is a three layer
hierarchical framework. The logical units of the management model
are Configuration, Site and Database Resources. These three layers
share a parent-child relationship as shown in Figure 2-3 below.
Figure 2.3 – The relation between layers of the
Broker management model.
A Database Resource is the smallest unit
managed by Data Guard Broker. In the Broker management model, a
database resource represents an instance of the primary or standby
database. In addition, a service such as the log apply service can
be classified as a database resource in the context of a management
model. The site in this model is a collection of database resources.
In other words, a site is equivalent to a host
machine on which a database instance is running. Configuration is
the largest unit in the Broker management model and consists of the
primary site and one or more standby sites.
Data Guard Broker can manage all three layers of the management
model. Any operation performed on a higher level of the model is
applicable to all child objects of that layer. For example, if the
status of a site is changed to offline, all the resources under that
site will be offline.