Presentation #36693
Oracle High Availability
Solutions in a Nutshell
Daniel T. Liu
Senior Technical Consultant
First American Real Estate Solutions
Date: Tuesday, September 10, 2003 @ 8:30 AM - 9:30 AM
Place: Moscone Room 104
Agenda
• Introduction
• High Availability
Concepts
• High Availability
Challenges
• High Availability
Solutions
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Agenda
• Oracle Advanced
Replication
• Oracle Real
Application Cluster
(RAC)
• Oracle Data Guard
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Agenda
• Oracle Streams
• Choose the Right
High-availability
Solutions
• Summary
• Q&A
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Introduction
• Why do we need to provide system and
database High Availability?
• Planned Downtime
– Database backup/upgrade/patching
– Operating system upgrade/patching
– Hardware and Network maintenance
• Unplanned Downtime
– Corruptions
• Logical corruptions
• Physical corruptions
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Introduction
• Unplanned Downtime
– Human Errors
• Accidentally drops, truncates a table
• Accidentally delete, update rows in a table
• Accidentally delete a data file or drop a
tablespace
– Disasters
•
•
•
•
War, terrorism
Earthquake, flood, fire or hurricane
No power for a long period
Server crash, malfunction of hardware
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High Availability Concepts
• What is High Availability?
– In the old days
• Local time
• Monday thru Friday
• 8 am to 6 pm
– Current environment
• Global
• 365 x 24 x 7
• Minimal downtime (planned or unplanned)
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High Availability Concepts
• Understanding High Availability
– Computing environments configured to provide
nearly full-time availability are known as high
availability systems.
– When failures occur, the failover process moves
processing performed by the failed component
to the backup component.
– The more transparent that failover is to users,
the higher the availability of the system.
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High Availability Concepts
• Measuring Availability
– The mean time to recover (MTTR)
– The mean time between failures (MTBF)
– Total uptime in a year (%)
Minutes of
Downtime
5
60
1440
2880
Minutes of
Uptime
525595
525540
524160
522720
Minutes in a Year
525600
525600
525600
525600
Total Uptime in a
Year (%)
99.9990%
99.9886%
99.7260%
99.4521%
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High Availability Challenges
• Challenges for Database High Availability
– Database size is getting bigger and bigger
– Database Backup Time
• A DLT tape writes 6 MB/Second, or 21 GB/hour
• A 2 TB database with one tape driver will take 97
hours to backup
– Database Recovery Time
– Is the backup good?
– Trouble shooting time
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High Availability Solutions
• Traditional High Availability Solutions
– Backup and restore
• High Availability Solutions
–
–
–
–
Oracle Advanced Replication
Oracle Real Application Clusters (RAC)
Oracle Data Guard (Standby Database)
Oracle Streams
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High Availability Solutions
• High Availability Solution means :
–
–
–
–
–
No Single Points-of –failure
Hardware Redundancy
Software Redundancy
Data Redundancy
Application Redundancy
– More ..
$?
– Save Money
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Oracle Advanced Replication
•
•
•
•
Advanced Replication Overview
Replication Components
Types of Replication Environments
Administration Tools for Replication
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Advanced Replication Overview
• Replication is the process of copying and
maintaining database objects, such as
tables, in multiple database .
• Changes applied at one site are captured
and stored locally before being forward
and applied at each of the remote
locations.
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Replication Components
• Replication Objects
– Table, Indexes, View
– Procedures, Packages, Functions, Triggers
– User-Defined Types
• Replication Groups
– A collection of replication objects that are logically
related.
– Master group
– Materialized view group
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Replication Components
• Replication Sites
– Master Sites
– Materialized View Sites
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Types of Replication
• Multimaster Replication
– Each master site operates as an equal peer.
– Provides complete replicas of each replicated
table at each of the master sites.
– Replicate changes for each transaction.
– Two types of multimaster replication
• Asynchronous
• Synchronous
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Asynchronous Data Replication
Source Database
Change
Destination Database
Replicated
Table
Replicated
Table
Trigger
Deferred
Transaction
Queue
Remote Procedure
Call
Procedure
Synchronous Data Replication
Source Database
Change
Destination Database
Replicated
Table
Trigger
Replicated
Table
Remote Procedure
Call
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Procedure
18
Types of Replication
• Materialized View Replication
– Replicate subset of master table data
– Batch-oriented operation (refresh)
– 3 types of materialized views
• Read-Only
• Updateable
• Writeable
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Materialized View Replication
Application
Update
Update
Update
Query
Master
Table
(updatable)
Master
Table
(updatable)
Master
Table
(updatable)
Refresh
Materialized
View
(read-only)
Refresh
Materialized
View
(updatable)
Refresh
Materialized
View
(writeable)
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Update
Update
20
Replication Administration Tools
• Oracle Enterprise Manager
– Replication Manager
• Oracle-Supplied PL/SQL packages
– DBMS_REPCAT
• Replication Catalog
– On every master sites
– Materialized view sites
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Oracle Real Application Clusters
(RAC)
•
•
•
•
•
Real Application Clusters Overview
Real Application Clusters Architecture
Real Application Clusters Components
Cache Fusion
Transparent Application Failover (TAF)
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Real Application Clusters
Overview
• Multiple instances against the same
database.
• Involves a cluster of nodes with access to
a set of shared disks through Cluster
Management Software (CMS).
• Oracle’s solution for system failures.
• Transparent Application Failover (TAF)
• Connection Load Balancing
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Real Application Clusters Architecture
Option 1
Option 2 (RAC)
Instance A
Instance B
DB1
DB3
Instance A
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interconnect
Instance B
DB1
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Real Application Clusters Architecture
SGA
SGA
Global
Resource
Directory
LMON
LMD
Global
Resource
Directory
Cluster
Interconnect
LMS
LMON
Instance A
LMD
Instance B
Cluster Group
Services
Cluster Group
Services
Vendor
CMS
Vendor
CMS
Node A
Node B
Local Disks
Oracle Software
Archived Logs
LMS
Shared Disks
Data Files
Control Files
Online Redo Files
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Local Disks
Oracle Software
Archived Logs
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Real Application Clusters
Components
•
•
•
•
•
Shared Disk
Vendor CMS
Cluster Group Services
Global Resource Directory
RAC Background Process
– LMON (Global Cache Service Process)
– LMD (Global Enqueue Service Daemon)
– LMS (Global Enqueue Service Monitor)
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Cache Fusion
• Oracle’s Global Cache Management
Technology.
• It provides cache to cache transfers of
data blocks between instances in a
cluster.
• It eliminates forced disk writes.
• Dynamic resource re-mastering
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Transparent Application Failover
(TAF)
• Little or no user downtime.
• Applications and users are automatically
and transparently reconnected to another
system.
• DML transactions are rolled back
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Oracle Data Guard
•
•
•
•
•
•
Data Guard History
Data Guard Components
Data Guard Roles
Data Guard Interfaces
Data Guard Process Architecture
Data Guard Protection Mode
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Data Guard History
• History of Standby Database
– Oracle7.3: First Release of Standby
Database
– Oracle8i: Automatic shipping and
application of redo logs
– Oracle9i Release 1: Protection mode
– Oracle9i Release 2: Logical standby
database
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Data Guard Components
• Primary Database
• Standby Database
– Physical Standby Database
– Logical Standby Database (9iR2 only)
•
•
•
•
Log Transport Services
Network Configuration
Log Apply Services
Data Guard Broker
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CLI
Primary
Database
Oracle Net
Data
Guard
Broker
Online
Redo
Logs
Local
Archived
Logs
GUI
Data
Guard
Broker
Log
Transport
Services
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Standby
Database
Log
Apply
Services
Remote
Archived
Logs
32
Data Guard Roles
A database can operate in one of the two
mutually exclusive roles:
• Failover
– One of the standby databases takes the
primary database role
• Switchover
– In Oracle9i, primary and standby
database can continue to alternate roles
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Data Guard Interface
• SQL*Plus and SQL Statements
SQL> alter database commit to switchover
to physical standby;
• Data Guard Broker GUI
– Data Guard Manager
• Data Guard Broker Command-Line Interface
$ dgmgrl
DGMGRL for Solaris: Version 9.2.0.1.0 Production.
(c) Copyright 2002 Oracle Corporation. All
rights reserved.
Welcome to DGMGRL, type "help" for information.
DGMGRL>
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Process Architecture
• Physical/Logical Standby Processes
–
–
–
–
–
LGWR (Log Writer) process
ARCH (Archiver) process
LNS (LGWR Network Server) process
RFS (Remote File Server) process
MRP (Managed Recovery) process
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Process Architecture
• Physical/Logical Standby Processes
–
–
–
–
–
FAL (Fetch Archive Log) Client process
FAL (Fetch Archive Log) Server process
LSP (Logical Standby) process
PX (Parallel Execution) process
DMON (Data Guard Broker Monitor) process
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Physical Standby Processes Architecture
Primary
Database
DMON
DMON
Physical
standby
Database
SYNC
LGWR
LNS
ASYNC
RFS
Oracle Net
Online
Redo
Logs
ARCH
Standby
Redo
Logs
ARCH
Local
Archived
Logs
FAL
Client/
MRP
Remote
Archived
Logs
FAL
Server
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Logical Standby Processes Architecture
DMON
Primary
Database
DMON
Logical
Standby
Database
SYNC
LGWR
LNS
RFS
Oracle Net
Online
Redo
Logs
ASYNC
PX
PX
Applying
Group
LSP0
ARCH
PX
Local
Archived
Logs
Remote
Archived
Logs
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PX
Mining
Group
38
Data Protection Mode
• Oracle9i Release 2 has three data protection modes
Mode
Log Writing
Process
Network
Trans Mode
Disk Write
Option
Redo Log
Reception
Option
Supported on
Maximum
Protection
LGWR
SYNC
AFFIRM
Standby redo
logs are
required
Physical
standby
databases
Maximum
Availability
LGWR
SYNC
AFFIRM
Standby redo
logs
Physical and
logical standby
databases
Maximum
Performance
LGWR or
ARCH
SYNC or
ASYNC
NOAFFIRM
Standby redo
logs
Physical and
logical standby
databases
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Oracle Streams
•
•
•
•
Oracle Streams Overview
Oracle Streams Process Architecture
Oracle Streams Rules
Administration Tools for Oracle Streams
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Oracle Streams Overview
• Oracle9i’s new replication product.
• Similar to logical standby database
• Changes are captured at source
Database.
• Propagate information within a database
or from one database to another.
• Using Message Queuing.
• Heterogeneous information sharing.
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Oracle Streams Process
Architecture
• Capture changes at a database.
• Enqueue events into a queue.
• Propagate events from one queue to
another.
• Dequeue events.
• Apply events at a database.
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Oracle Streams Processes Architecture
Source
Database
Redo
Log
Capture
Source Queue
Target Queue
LCR
LCR
User
Message
User
Message
LCR
LCR
..
..
..
LCR
LCR
User
Message
User
Message
LCR
LCR
..
..
..
Enqueue
Propagate
Dequeue
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Target
Database
Apply
43
Oracle Streams Rules
• Rules are used to control which information to
share and where to share it.
• Rules can be used during capture, propagate,
and apply processes.
• Rules can define in three level:
– Table
– Schema
– Global
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Oracle Streams Administration
Tools
• Oracle-Supplied PL/SQL packages
–
–
–
–
DBMS_STREAMS_ADM
DBMS_CAPTURE_ADM
DBMS_PROPAGATION_ADM
DBMS_APPLY_ADM
• Streams Data Dictionary views
– DBA_APPLY
– V$STREAMS_CAPTURE
• Oracle Enterprise Manager
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Choose High-Availability
Solution
• Product Licensing
• Unsupported Datatype
• Feature Comparison
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Product Licensing
High Availability Product Enterprise Edition
Advanced Replication
Included
Real Application Clusters
Additional License Fee
Data Guard
Included
Streams
Included
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Unsupported Datatype for
Logical Standby and Streams
Supported Datatypes
Unsupported Datatypes
CHAR, NCHAR
VARCHAR2, NVARCHAR2
NUMBER
DATE
CLOB,BLOB
RAW
TIMESTAMP
TIMESTAMP WITH TIME ZONE
TIMESTAAMP WITH LOCAL TIME ZONE
INTERVAL YEAR TO MONTH
INTERVAL DAY TO SECOND
NCLOB
LONG
LONG RAW
BFILE
ROWID
UROWID
User-defined types
Object types
- REFS
- Varrays
- Nested tables
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Feature Comparison
Advanced RAC Physical Logical Streams
Replication
Standby Standby
Entire
Database
Replication
Schema
Replication
Table
Replication
YES
N/A
YES
YES
YES
YES
N/A
NO
NO
YES
YES
N/A
NO
NO
YES
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Feature Comparison
Advanced RAC Physical Logical Streams
Replication
Standby Standby
DML
Replication
YES
N/A
YES
YES
YES
DDL
Replication
YES
N/A
YES
YES
YES
Instance
Redundant
YES
YES
YES
YES
YES
Database
Redundant
YES
NO
YES
YES
YES
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Feature Comparison
Advanced RAC Physical Logical Streams
Replication
Standby Standby
Cluster
Management
Software
Failover
Mechanism
Load
Balancing
NO
Manual
Failover
YES
YES
NO
NO
NO
Manual
Failover
Failover
TAF
Switchover Switchover Failover
YES
YES
Partial
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YES
YES
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Feature Comparison
Advanced RAC Physical Logical Streams
Replication
Standby Standby
Change
Captured
Local
Heterogeneous
Database
Support
YES
NO
NO
NO
YES
Datatype
Support
ALL
ALL
SOME
SOME
SOME
Local Remote Remote
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Local
52
Feature Comparison
Advanced RAC
Replication
OS Platform
between
source and
Target
Can be
Different
Must
be
Same
Oracle
Version
Between
Source and
Target
Can
be
Different
Must
be
Same
Physical Logical Streams
Standby Standby
Must
be
Same
Must
be
Same
Can be
Different
Must
be
Same
Must
be
Same
Can
be
Different
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Summary
• High Availability Concept
• High Availability Options
–
–
–
–
Advanced Replication
Real Application Clusters
Data Guard
Oracle Streams
• High Availability Product Comparison
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References
Oracle9i, Data Guard Concepts and Administration. Release 1 (9.0.1);
Oracle9i, Data Guard Concepts and Administration. Release 2 (9.2);
Oracle9i, Data Guard Broker. Release 2 (9.2);
Oracle9i, Real Application Clusters, Concepts. Release 1 (9.0.1);
Oracle9i, Advanced Replication. Release 2 (9,2);
Oracle9i, Streams. Release 2 (9.2);
Oracle Metalink Support;
Top DBA Shell Scripts for Monitoring Database, Daniel T. Liu; DBAZine;
I would also like to acknowledge the assistance of Larry Barry, Ann
Collins, Archana Sharma and Husam Tomeh of FARES, and Larry
Carpenter, Joseph Meeks, Roger Peterson of Oracle Corporation.
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Thanks For Coming !!
Daniel Liu Contact Information
Phone: (714) 701-3346
Email: dliu@firstam.com
Email: daniel_t_liu@yahoo.com
Company Web Site:
http://www.firstam.com
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