DG

1. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
Introduction to Oracle Data Guard

2. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 2
Objectives
After completing this lesson, you should be able to:
• Describe the basic components of Oracle Data Guard
• Explain the differences between physical and logical
standby databases
• Explain the benefits of implementing Oracle Data Guard

3. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 3
What Is Oracle Data Guard?
Primary
database
Standby
database
Database Database
copy
Redo transport
Oracle
Net

4. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 4
Types of Standby Databases
• Physical standby database:
– Is identical to the primary database on a block-for-block
basis
– Is synchronized with the primary database through
application of redo data received from the primary database
– Can be used concurrently for data protection and reporting
• Logical standby database
– Shares the same schema definition
– Is kept 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
– Can be used concurrently for data protection, reporting, and
database upgrades

5. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 5
Types of Standby Databases
• Snapshot standby database:
– Is a fully updatable standby database
– Is created by converting a physical standby database
– Can be used for updates, but those updates are discarded
before the snapshot standby database is converted back into
a physical standby database
– Can be used for testing

6. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 6
Types of Data Guard Services
Data Guard provides three types of services:
• Redo transport services
• Apply services
– Redo Apply
– SQL Apply
• Role management services

7. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 7
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
– Emergency use
– Zero or minimal data loss (depending on choice of data-
protection mode)
– Can be initiated automatically when fast-start failover is
enabled

8. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 9
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

9. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 10
Choosing an Interface for Administering
a Data Guard Configuration
• Data Guard broker configuration:
– DGMGRL command-line interface
– Enterprise Manager Cloud Control
– SQL commands to query data dictionary views
• Non–Data Guard broker configuration:
– SQL commands

10. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 11
Oracle Data Guard: Architecture
(Overview)
Primary
database
transactions
Online
redo
logs
ARC0
RFS
MRP or
LSP
Archived redo
logs
ARC0
Standby
database
Reports
Standby
redo logs
Archived redo
logs
Backup
Oracle
net
LNSn
(Real-time
apply)
LGWR
Redo
buffer
Gap
resolution

11. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 12
Primary Database Processes
Primary
database
transactions
Online
redo
logs
ARCn
RFS
MRP or
LSP
Archived redo
logs
ARCn
Standby
database
Reports
Standby
redo logs
Archived redo
logs
Backup
NSSn
(Real-time
apply)
LGWR
Redo
buffer
Gap
resolution
Oracle
net

12. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 13
Standby Database Processes
Primary
database
transactions
Online
redo
logs
ARCn
RFS
MRP or
LSP
Archived redo
logs
ARCn
Standby
database
Reports
Standby
redo logs
Archived redo
logs
Backup
NSSn
(Real-time
apply)
LGWR
Redo
buffer
Oracle
net
Gap
resolution

13. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 14
Physical Standby Database:
Redo Apply Architecture
Production
database
Physical standby
database
Redo
apply
Redo
stream
Redo
transport
Backup
Physical standby
database
Primary
database

14. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 15
Logical Standby Database:
SQL Apply Architecture
Primary
database
Transform redo
information into
SQL
SQL
Apply
Reports
Production
database
Logical standby
database
Logical standby
database
Redo
transport

15. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 16
Automatic Gap Detection and Resolution
Primary
database
transactions
Online
redo
logs
ARC0
RFS
MRP or
LSP
Archived redo
logs
ARC0
Standby
database
Reports
Standby
redo logs
Archived redo
logs
Backup
LNSn
(Real-time
apply)
LGWR
Redo
buffer
ARCH ping
Redo to
resolve
gap
Oracle
net

16. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 17
Data Protection Modes
Select the mode to balance cost, availability, performance, and
data protection:
• Maximum protection
• Maximum availability
• Maximum performance

17. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 19
Data Guard Operational Requirements:
Hardware and Operating System
Primary database systems and standby database systems
may have different:
• CPU architectures
• Operating systems
• Operating system binaries (32-bit or 64-bit)
• Oracle Database binaries (32-bit or 64-bit)
Many restrictions exist.

18. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 20
Data Guard Operational Requirements:
Oracle Database Software
• The same release of Oracle Database Enterprise Edition
must be installed for all databases except when you
perform a rolling database upgrade by using a logical
standby database.
• If any database uses ASM or OMF, all databases should
use the same combination.

19. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 21
Benefits of Implementing
Oracle Data Guard
Oracle Data Guard provides the following benefits:
• Continuous service during disasters or crippling data
failures
• Complete data protection against corruption and data loss
• Elimination of idle standby systems
• Flexible configuration of your system to meet requirements
for business protection and recovery
• Centralized management

20. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 22
Quiz
Which of the following are types of standby databases?
a. Physical
b. Primary
c. Logical
d. Snapshot

21. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 23
Quiz
What is the maximum number of standby databases supported
by the Data Guard Broker?
a. 10
b. 20
c. 30
d. 40

22. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 24
Summary
In this lesson, you should have learned how to:
• 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

23. Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
1 - 25
Practice 1: Overview
This practice covers the following topics:
• Introducing the lab environment
• Starting and stopping a virtual machine
• Starting and stopping the Oracle Management Server
• Starting and stopping the Oracle Agent
• Accessing Oracle Enterprise Manager