Data Guard Client-side Broker Tips Oracle Tips by Burleson Consulting December 3, 2011

Data Guard

Question:  What are the Client Side Components of the Data Guard Broker?  I understand that the data guard broker has both client-side and server-side components and these work together.

Answer:  The Data Guard Manager and Command Line Interface (DGMGRL) make up the client side components of Data Guard Broker.  Data Guard Manager is a graphical user interface that is integrated with the Oracle Enterprise Manager (OEM). It contains several wizards that are used to ease the management of a Data Guard configuration. DGMGRL or Command Line Interface provides most of the functionalities of Data Guard Manager and can be useful in writing custom scripts to automate Data Guard tasks.

Role of the Transport Network Substrate in broker communication

Oracle SQL*Net services play an important role in the performance of standby databases. It acts as communication channel between primary and standby databases. In order for the log transfer service, automatic archive gap resolution and role management service to work without manual intervention, an Oracle Net connection between the primary and the standby site must be maintained.

Oracle SQL*Net is not required when a standby database is running in manual recovery mode. However, given the limitations and high degree of DBA intervention required in the manual recovery mode, that particular structure would not be an obvious choice.

SQL*Net can be configured to connect sites over a LAN or a WAN.  Good network bandwidth should be provided in order to achieve better performance of the log transfer service. In addition to connecting the primary site to all of its standby sites through SQL*Net, it is a good practice to connect the standby sites with each other. This will minimize the downtime during switchover or failover operations.
 
The Oracle Name services on the primary site should be configured such that the archiver process can resolve the service name for archiving to a remote standby destination. Moreover, the listener on standby sites should be configured properly to respond to the request sent by the archiver process of the primary site. The details about the configuration of SQL*Net services in context of Data Guard configuration are provided in the next chapter.
 
This chapter included a quick architectural overview of the Oracle Data Guard and standby databases. In general, the following topics were covered in order to build the foundation for the rest of this book:

- Detail about Oracle processes and files involved in the working of Data Guard have been presented.

- The redo log apply service for physical and logical standby databases were included, in detail.

- A brief description of Log Miner technology, which forms the backbone of the SQL apply mode, was provided.

- The concept of archive gap sequences and how they are detected and resolved in Oracle was covered in detail.

- A complete section on Data Guard Broker provided broker architecture information along with other core concepts.

- The importance of SQL*Net in the context of Data Guard has been included, in brief.

A review of the first two chapters should provide a clear picture of Data Guard and standby databases. Most of the concepts discussed in these chapters will be elaborated upon in the remainder of this book.