Understanding the Oracle Data Guard Architecture

Understanding the OracleData Guard Architecture

Objectives • After completing this lesson, you should be able to do the following: • Describe the Data Guard architecture • Explain the operational requirements of Data Guard • Describe how Data Guard processes, transports, and applies redo logs • Describe standby database modes

Data Guard Operational Requirements: Hardware and Operating System • The hardware can be different for the primary and standby databases. • The operating system and platform architecture for the primary and standby databases must be the same. • The operating system releases for the primary and standby databases can be different. • If all databases are on the same system, verify that the OS allows you to mount more than one database with the same name.

Data Guard Operational Requirements: Oracle Database Software • Same release of Oracle Database Enterprise Edition must be installed for all databases. • SYSDBA privileges are required for the accounts used to manage the database instances. • Each database must have its own control file. • Primary database must operate in ARCHIVELOG mode. • Enable FORCELOGGING on the primary database before taking data file backups for standby creation. • If any databases use ASM and/or OMF, all should use the same combination.

Oracle Data Guard: Architecture Primary database transactions MRP or LSP Standby database (MRP only) LNSn LGWR RFS (Real-time apply) Oracle net Online redo logs Standby redo logs Backup Reports FAL ARC0 ARC0 Archived redo logs Archived redo logs

Primary Database Flow Primary database transactions MRP or LSP Standby database (MRP only) LNSn LGWR RFS (Real-time apply) Oracle net Online redo logs Standby redo logs Backup Reports FAL ARC0 ARC0 Archived redo logs Archived redo logs

Standby Database Flow Primary database transactions MRP or LSP Standby database (MRP only) LNSn LGWR RFS (Real-time apply) Oracle net Online redo logs Standby redo logs Backup Reports FAL ARC0 ARC0 Archived redo logs Archived redo logs

Standby Redo Logs Standby redo logs Archived redo logs Redo from primary database ARC0 RFS MRP/LSP Standby database

Physical Standby Database: Redo Apply Architecture Production database Physical standby database Redo transport Redo apply Redo stream Backup Primary database Physical standby database

Logical Standby Database:SQL Apply Architecture Production database Logical standby database SQL Apply Redo transport Transform redo information into SQL Reports Primary database Logical standby database

SQL Apply Process: Architecture LCRLCR: Preparer Reader Builder Shared pool Redo records Redo data from primary database Logical change records not grouped into transactions Transaction groups Log Mining Apply processing Analyzer Applier Coordinator Transactions sorted in dependency order Transactions to be applied Data files

Real-Time Apply RFS MRP or LSP Primary database Standby redo log files ARC0 Archived redo log files Standby database

Setting the DB_UNIQUE_NAME Parameter San Francisco SF1_DB DB_UNIQUE_NAME = SF1_DB

Specifying Role-Based Destinations Primary database Standby database Not used LOG_ARCHIVE_DEST_2= location= "/u01/app/oracle/oradata/orcldg2/arc", valid_for=(STANDBY_LOGFILE,STANDBY_ROLE) DB_UNIQUE_NAME = HRDB2

Combinations for VALID_FOR

Identifying Destination Settings SQL> SELECT DEST_ID,VALID_TYPE,VALID_ROLE,VALID_NOW 2 FROM V$ARCHIVE_DEST; DEST_ID VALID_TYPE VALID_ROLE VALID_NOW ------- --------------- ------------ -------------- 1 ALL_LOGFILES ALL_ROLES YES 2 STANDBY_LOGFILE STANDBY_ROLE WRONG VALID_TYPE 3 ONLINE_LOGFILE STANDBY_ROLE WRONG VALID_ROLE 4 ALL_LOGFILES ALL_ROLES UNKNOWN 5 ALL_LOGFILES ALL_ROLES UNKNOWN 6 ALL_LOGFILES ALL_ROLES UNKNOWN 7 ALL_LOGFILES ALL_ROLES UNKNOWN 8 ALL_LOGFILES ALL_ROLES UNKNOWN 9 ALL_LOGFILES ALL_ROLES UNKNOWN 10 ALL_LOGFILES ALL_ROLES UNKNOWN 11 ALL_LOGFILES ALL_ROLES YES 11 rows selected.

Standby Redo Log Configuration Online redo logs Standby redo logs Redo shipment RFS Primary database Standby database

Using SQL to Add Standby Redo Logs • Use the ALTERDATABASE statement to create the standby redo log files: • Add members to a group with the following statement: • View information about the groups as follows: SQL> ALTER DATABASE ADD STANDBY LOGFILE 2 ('/oracle/oradata/orcl/log1c.rdo', 3 '/oracle/oradata/orcl/log2c.rdo') SIZE 500K; SQL> ALTER DATABASE ADD STANDBY LOGFILE MEMBER 2 '/oracle/oradata/orcl/log2b.rdo' TO GROUP 2; SQL> SELECT * FROM v$standby_log; SQL> SELECT * FROM v$logfile 2 WHERE type = 'STANDBY';

Using Enterprise Managerto Add Standby Redo Logs

Standby Database Modes • You can maintain the standby data in one of the following modes: • For physical standby databases • Redo Apply • Open read-only mode • For logical standby databases • Open read/write mode

Summary • In this lesson, you should have learned how to describe the following: • Data Guard architecture processes • Operational requirements of a Data Guard environment • How Data Guard processes, transports, and applies redo logs • Modes of standby databases and when to use each mode

Practice 2-1: Architecture Review • This practice covers the following topics: • Reviewing the Oracle Data Guard architecture • Reviewing the processes that Data Guard uses to transport and apply redo logs • Reviewing the modes that are used to recover a primary database

Practice 2-2: Installing the Oracle Management Agent • This practice covers the following topics: • Installing the Oracle Management Agent • Configuring monitoring credentials for your database

Practice 2-3: Configuring Your Primary Database • This practice covers the following topics: • Reviewing your primary database configuration • Configuring your primary database in preparation for creating a Data Guard configuration

Understanding the Oracle Data Guard Architecture