1.Let us we discuss what is purpose we have to learn Oracle RAC11g?
*Before we are discussing what is OracleRAC and what are the benefits of RAC we will the life cycle of " OracleDba " has shown in the pic below
*The most people are reading this blog the who is already oracle dba or they are trying to become an oracle dbathe person who is started his career at Linux administrator or he had a good knowledge of Linux than he stepped into oracle dba (most of them knows what is oracle dba and what they are doing we are not discussing about entire thing but we will focus outline ).
*It classified into two types
*the one who works on outside SQLPLUS i.e creating DB backup strategies, config dg, install /uninstall DB, restore backup, patching, performing upgrades
* the one who works on inside the SQLPLUS i.e user data, cloning database, create database or table/index /schema refresh/copying one into another DB
*The guy one who has 4 years experience what is next? their next preferences to learn Oracle RAC, before we are going to know about ORACLE RAC we would see the architecture of standalone and ORACLE RAC?
*1 RAM and 1 HDD the user send request stand-alone machine it will go to RAM(Oracle instance )it doesn't fetch the data directly from HDD(Hard Disk) so the instance will fetch data from HDD and respond to user request
*In case our HDD got an issue or failure we can lose the data even if we have a backup also we would miss the current working data and moreover we need to again install os, software so the traditional days we would follow the method of "Redundancy"
What is the redundancy?
*It means redundant which is having a support or kind of backup
*Each data has been written to hard disk, at the same time data has copied into another base so the data won't lose at all
*But the current working data was stored in RAM only if we a have failure in RAM we would lose the data at the same time we cant redundant RAM
*Basically we dba what will think of the problem of above actually, the dataguard provide give assurance for 100% without data loss but its only for committed redo logs not for archive logs which is resides on RAM.
*It needs manual intervention to switch over or fail over the server so basically the time period of the production server was not available for users it's called "Downtime"
I)if we have issue with DG it will take time "switchover/failover" standby (Which means it 'll provide no data loss which is committed but it can't assurance for high availability) it 'll take time make available to users
II) Archive log is loss on standby server
III) Site Failure
*The Oracle resolve the issue of "Downtime" so it maintains separate hard disk (Shared Storage) like given below
*In this pic the client-server are interconnected the data which was committed data are maintained in shared storage so the client will access data from shared storage i.e now data has been independent
*Even the client was loss the data it 'll pass through the connection to another client-server so there is no downtime
*The Oracle RAC Is a solution for server failure
The Benefits of learning RAC we will learn some new things also:
5)Oracle RAC Administration
Source: Oracle Website ,Google