Data Guard Physical Standby and Logical Standby Database Architecture in...

In this tutorial, we will learn
-Types of Standby Databases
-Background Services
-Data Guard Architecture
-Protection mode of Data Guard

Types of Standby Database
-Physical Standby
-Logical Standby

Discuss Later
Snapshot Standby
Active-Standby

Background Process work behind the Data Guard Configuration
*LNS - Log Network Service ( Running on the Primary Database)
*RFS - Remote File Service (Running on the Standby Database)
*MRP - Media Recovery Process (Running on the Standby Database)
*LSP - Logical Standby Process (Running on Logical Standby Database)

Standby
*Standby is a block to block a copy of the production database.
*The Standby Database also called is Physical Standby.
*The MRP process Manage the recovery which applies the received redo on physical standby.

Logical Standby
*Convert received redo in SQL statement and execute on standby.
*Logical standby database read/write operations (not on the replicated tables)
*Structure not same .
*Involve a few extra processes.
*Not all data types are supported.

Redo Transport Services
*SYNC - Synchronous Redo Transport
*ASYNC - Asynchronous Redo Transport

Note:- Both have the same responsibility to transport redo from production to standby.

SYNC - Synchronous Redo Transport
*Zero Data Loss
*Performance impact

ASYNC - Asynchronous Redo Transport
*Data Loss
*Zero performance impact

Protection mode for Data Guard
Maximum Performance
*It uses ASYNC redo transport
*Priority given to performance
*Minimum data loss


Maximum Availability
*It uses SYNC redo transport (Required)
*First Priority given availability and second priority is data protection
*If standby not available, the primary will wait and then proceed

Maximum Protection
*It uses SYNC redo transport (Required)
*Zero data loss
*If standby not available, the primary will be hangs and database will be abort
*Suggested more than one standby configured

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