what is data guard

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DATA GUARDDATA GUARD

PRESENTATIONPRESENTATION

FOR FOR

SIX MONTHS INDUSTRIAL TRAININGSIX MONTHS INDUSTRIAL TRAINING

FROMFROM

SQL TECHNOLOGIESSQL TECHNOLOGIES

ONON2222NDND APRIL 2010APRIL 2010

PRESENTED BY,PRESENTED BY,

RAMAN BRAR RAMAN BRAR

G.T.B.K.I.E.T(MALOUT)G.T.B.K.I.E.T(MALOUT)

BATCH 06BATCH 06



What is Data Guard?What is Data Guard?

It is the management, monitoring andIt is the management, monitoring and

automation s/w that works with a productionautomation s/w that works with a production

database and one or more standby databases todatabase and one or more standby databases toprotect your data against failures,errors andprotect your data against failures,errors and

corruptions that might otherwise destroy your corruptions that might otherwise destroy your

database.database.



Disaster R ecovery Food chainDisaster R ecovery Food chain

users applicationsnetworks servers databases

DA

T

A

G

U

A

R

D



Advantages of Proposed System Advantages of Proposed System

Aga

inst

Existing

Sy

stem

Aga

inst

Existing

Sy

stem

TThis system provides high availability for DBhis system provides high availability for DB

serversservers

R R educe the human intervention required toeduce the human intervention required toswitch DBs at disaster recoveryswitch DBs at disaster recovery

TThis system reduces the manpower his system reduces the manpower

TThis system acts as an automation toolhis system acts as an automation tool

IIt provides complete data protectiont provides complete data protection



Need of ProjectNeed of Project

LLower cost and complexityower cost and complexity

MMaximum return on investmentaximum return on investment

MMaximum protectionaximum protection MMaximum availabilityaximum availability

MMaximum performanceaximum performance



Project ObjectivesProject Objectives

IIt provides an efficient and comprehensive disaster t provides an efficient and comprehensive disaster

recovery and high availability sol¶nrecovery and high availability sol¶n

IIt provides an effective safeguard against datat provides an effective safeguard against data

corruptions and user errorscorruptions and user errors

IIf connectivity is lost b/w primary and standbyf connectivity is lost b/w primary and standby

databases Data Guard will automatically reconnectdatabases Data Guard will automatically reconnect

and resynchronize the standby databaseand resynchronize the standby database IIt is available as an integrated feature of the oraclet is available as an integrated feature of the oracle

database at no extra costdatabase at no extra cost



Types of Standby DatabasesTypes of Standby Databases

Supported

By

Data

Guard

Supported

By

Data

Guard

A Logical standby database is logically identical tothe primary database and can be used as a productiondatabase if the primary database is taken offline for routine maintenance or is damaged through human

error, corruption, or a disaster. A Physical standby database has its roots in media

recovery. It must be physically identical to theprimary database.The database schema, including

indexes, must be the same, and the database cannot beopened for updates. If opened for updates, thestandby database would have different row IDs,making continued recovery impossible.



Log Apply Services For Physical &Log Apply Services For Physical &

Logical

Sta

nd

by

Data

ba

ses

Logical

Sta

nd

by

Data

ba

ses



Advantages of Standby DatabaseAdvantages of Standby Database

VVery low failure rateery low failure rate

VVery short downtimeery short downtime

SSignificant decrease of load on the productionignificant decrease of load on the productionhosthost

AApplying redo log files to standby databasepplying redo log files to standby database

immediately verifies their consistencyimmediately verifies their consistency



Disadvantages of Standby DatabaseDisadvantages of Standby Database

HHigh costigh cost

HHigh system administration epenseigh system administration epense

HHigh requirement for switch over and failover igh requirement for switch over and failover s/ws/w



Data Guard Conf igurationData Guard Conf iguration



Physical Standby differs from Physical Standby differs from

Logical

sta

nd

by

a

s:Log

ical

sta

nd

by

a

s:--

PPhysical standby schema matches exactly thehysical standby schema matches exactly the

source databasesource database

AArchived redo logs and FTP'ed directly to therchived redo logs and FTP'ed directly to thestandby database which is always running instandby database which is always running in

"recover" mode. Upon arrival, the archived"recover" mode. Upon arrival, the archived

redo logs are applied directly to the standbyredo logs are applied directly to the standby

databasedatabase



Logical Standby is different from Logical Standby is different from

Phy

sical

Sta

nd

by

a

s:Phy

sical

Sta

nd

by

a

s:--

LLogical standby database does not have to match theogical standby database does not have to match the

schema structure of the source databaseschema structure of the source database

LLogical standby transform the archived redo logs intoogical standby transform the archived redo logs into

native DML statements (insert, update, delete). Thisnative DML statements (insert, update, delete). This

DML is transported and applied to the standbyDML is transported and applied to the standby

databasedatabase

LLogical standby tables can be open for SQL queriesogical standby tables can be open for SQL queries

(read only), and all other standby tables can be open(read only), and all other standby tables can be open

for updatesfor updates



Data Guard ArchitectureData Guard Architecture



R ole ExchangeR ole Exchange

On Primary m/cOn Primary m/c

Alter database commit Alter database commit

to switchover toto switchover to

physical standby withphysical standby with

session shutdown;session shutdown;

On Standby m/cOn Standby m/c

Alter database recover Alter database recover

managed standbymanaged standby

database cancel;database cancel;

Alter database commit Alter database commit

to switchover to primaryto switchover to primary

with session shu;with session shu;



Operational R equirementsOperational R equirements

The primary database must run in archive log mode

Use the same database release on the primaryand standby databases

The hardware and operating systemarchitecture on the primary and standby

locations must be the same Each primary database and standby database

must have its own control f ile.



To protect against unlogged direct writes in

the primary database that cannot be propagated

to the standby database, turn on FORCE

LOGGING at the primary database before

taking datafile backups for standby creation.

Keep the database FORCE LOGGING mode

as long as the standby database is required.



TH ANK Y OU.TH ANK Y OU.

what is data guard

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