Oracle Database 10g: Data Guard
Administration
Electronic Presentation
D17316GC20
Edition 2.0
October 2006
D47658
®
Copyright © 2006, Oracle. All rights reserved.
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Author
Donna K. Keesling
Technical Contributors
and Reviewers
Christopher D. Andrews
Harald van Breederode
Larry Carpenter
Michael Cebulla
Joel Goodman
Editors
Arijit Ghosh
Daniel Milne
Graphic Designer
Satish Bettegowda
Publishers
Srividya Rameshkumar
Jobi Varghese
Copyright © 2006, Oracle. All rights reserved.
Oracle Data Guard: Overview
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1 - 2
Objectives
After completing this lesson, you should be able to do the
following:
• Describe the factors that affect planned and unplanned
downtime
• Describe the basic components of Oracle Data Guard
• Explain the differences between physical and logical

standby databases
• Explain the benefits of creating a Data Guard
environment
• Explain the use of Data Guard in high-availability
architectures
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1 - 3
Causes of Data Loss
Source: Disaster Recovery Journal
Natural disasters
3%
Software corruption
4%
Computer viruses 7%
Human errors 36%
Hardware & system errors 49%
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1 - 4
Understanding the Causes of Downtime
Planned
downtime
Unplanned
downtime
System
changes
Data
changes
Data
failures
Computer

failures
Corruption
Human
error
Site
failure
Storage
failure
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1 - 5
What Is Oracle Data Guard?
Primary
database
Standby
database
Database Database
copy
Redo transport
Oracle Net
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1 - 6
Types of Standby Databases
There are two types of standby databases:
• Physical standby database
– Identical to the primary database on a block-for-block
basis
– Synchronized with the primary database through
application of redo data received from the primary
database
• Logical standby database

– Shares the same schema definition
– Synchronized with the primary database by transforming
the data in the redo received from the primary database
into SQL statements and then executing the SQL
statements
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1 - 7
Oracle Data Guard Broker Framework
CLI management client
Enterprise Manager
Repository
Primary
database
Data
Guard
broker
Oracle
Management
Server
Data
Guard
broker
Agent
Standby
database
Agent
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1 - 8
Types of Services
There are three types of services provided with Data

Guard:
• Redo transport services
• Log apply services
– Redo Apply
– SQL Apply
• Role-management services
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1 - 9
Role Transitions: Switchover and Failover
• Oracle Data Guard supports two role-transition
operations:
– Switchover
—
Planned role reversal
—
Used for OS or hardware maintenance
– Failover
—
Unplanned role reversal
—
Use in emergency
—
Zero or minimal data loss depending on choice
of data protection mode
—
Can be initiated automatically when fast-start failover is
enabled
• Role-transition operations are not automatically
invoked.
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1 - 11
Data Protection Modes
• Maximum protection
• Maximum availability
• Maximum performance
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1 - 13
Benefits of Implementing
Oracle Data Guard
Oracle Data Guard provides the following benefits:
• Continuous service through disasters or crippling data
failures
• Complete data protection against corruptions and data
loss
• Efficient use of system resources
• Elimination of idle standby systems
• Flexible configuration of your system to meet business
protection and recovery requirements
• Centralized management
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1 - 14
Role of Data Guard in a
High-Availability Architecture
RAC
ASM
Flashback
technology
Data
failures
Computer

failures
Corruption
Human
error
Site
failure
Storage
failure
Oracle HARD
RMAN
Data Guard
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1 - 15
Role of Data Guard in a
High-Availability Architecture
Data
changes
System
changes
• Online schema and
data reorganization
• Partitioned tables
and indexes
• Dynamic resource
provisioning
• Rolling patch updates
• Rolling release upgrade
using Data Guard
SQL Apply
Planned

downtime
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1 - 16
Oracle Data Guard and
Real Application Clusters
Oracle Data Guard and Real Application Clusters are
complementary and can be used together.
• Real Application Clusters provides high availability.
• Oracle Data Guard provides disaster protection and
prevents data loss.
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1 - 17
Maximum Availability Architecture
RAC
production
database
RAC
physical
standby
database
Oracle
Application
Server
Oracle
Application
Server
WAN traffic
manager
Clients
Data Guard

RAC
logical
standby
database
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1 - 18
Summary
In this lesson, you should have learned how to:
• Describe the basic components of Oracle Data Guard
• Describe the differences between physical and logical
standby databases
• Determine when Oracle Data Guard is an appropriate
solution in your Oracle Database configuration
• Explain the use of Data Guard in high-availability
architectures
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1 - 19
Practice 1: Overview
This practice covers the following topics:
• Reviewing the factors that affect planned and
unplanned downtime
• Reviewing the differences between physical and logical
standby databases
• Reviewing the components of Oracle Data Guard
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Understanding the Oracle
Data Guard Architecture
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2 - 2
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
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2 - 3
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.
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2 - 4
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 FORCE LOGGING 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.
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2 - 6
Oracle Data Guard: Architecture
LGWR
Primary
database
transactions
Online
redo
logs
ARC0
FAL
RFS
MRP or
LSP
Archived redo
logs
ARC0
Standby
database
Reports
(MRP only)
Standby
redo logs
Archived redo
logs

Backup
Oracle net
LNSn
(Real-time
apply)
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2 - 7
Primary Database Flow
LGWR
Primary
database
transactions
Online
redo
logs
ARC0
FAL
RFS
MRP or
LSP
Archived redo
logs
ARC0
Standby
database
Reports
(MRP only)
Standby
redo logs
Archived redo

logs
Backup
Oracle net
LNSn
(Real-time
apply)