2.Overview of Oracle RAC :
SMP vs cluster
single processor machine(symmetric multiprocessing):
*It involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance.
*SMP is single processing machine / single processor machine basically all of our desktops, laptop because it have dedicated ram, dedicated hard disk, and processor
*It acts as one single system
*it consists of multiple systems which are connected each other to solve the business problem
* ex: if we search the query in google it means the single system responds to my query, actually it behind a lot of servers are connected and gives respond for users request outside of the world it seems one big system.
Cluster Management software:
*If we are going to use word file we need ms office software, at the same, we are going to access pdf files we need the pdf reader like the same we need to make multiple systems are connected each we need a software which name is called"Clusterware management software".
Benefits of Clusterware:
*scale up/ scale down
Types of the cluster:
1 active - active
*Clusterware provided by Oracle
*In market types of market
*Linux clustering software
*Solaris clustering software
*Veritas clustering software
*Both servers are live
2 active - passive
*it very less usage
*source has been waste
*MS SQL server cluster
To active the newly added logfile run this command
*Node level dependency is removed using shared storage
*In Oracle cluster ware has called grid if the node was down it would handle existing connection for certain group "Select" which was quiring into shared storage it automatically transferred into node2 and it would respond the user request.
*But it would not handle "Update" and "delete" the user terminal will exist without any performance on database so the user has to establish new connection the entire process is called "TAF"
*The cluster ware software would distribute the connection to all the nodes for ex: if we have two node machines the newly 10 connections are trying access the machine the cluster ware would distribute to each node this is called "Load Balance" and but if the user connects the node it processing the node it wont take or distribute processing of other nodes
What is ORACLE RAC?
*It is an oracle database software required for oracle Clusterware install
*It provides better performance and high availability
*It allows multiple computers run RDBMS simultaneously while accessing the single database.
Whatis Clusterware and grid?
*In oracle 9i it reduces the issue and released the name of "CRS"
*in oracle 10g the oracle released first own Clusterware software so the compatibility issues also solved and the Clusterware software name is "Grid".
What is the node?
*All computers are called as node in RAC
*Each node has separate database instance with its own background process and memory structure
Node: in standalone we can maintain the different name for instance and database in real time military application instance is different and the database name is different because it is to prevent from hackers.
*In rac environment each node has like the follow 1.os 2.grid (cluster ware) 3.Oracle software(Rac for cluster environment)
*in which the both nodes name are different it can access the data from shared storage over the network
Note:in Rac environment the database was there in shared storage (which name is prodb) if we assign the name of the nodes by manually if we forgot the name of nodes it ll became complexity so oracle resolve this complexity by assigning name (means if we had four nodes (n1,n2,n3,n4) it default assign the instance name of each node like proddb1,proddb2,proddb3,proddb4)
*Instance name is taken care by ORACLE RAC
*we can add/remove the node easily on the go easily thus providing scale up/down