Concept of VIP in Oracle RAC - SCAN part 1 - RAC 03

[Music] in Oracle database 11g release to Oracle brought about a host of features one of the major changes was the implementation of scan single client access name what is this mean is not understood by many people so this video and the next video will help you understand this before we move into understanding what is a scan let us understand how an application connects and works an application when it connects it contacts a listener and would have to then get connected to the instance when you have an re C setup where you have two nodes there are going to be two instances running on two different holes both the horse will have their own respective IP addresses plus additional e cluster where the software that manages the cluster would have also something called as a virtual IP address or a VIP that it will assign to both the nodes now when one of the instances goes down the virtual IP will fail over to the other mode thereby when a request comes to connect to the VIP it can communicate back saying that node is down and hence the client can now connect to another node how will the client connect to the other node going back to the client connectivity settings on the application you would now have not just a single host name specified instead you will list down all the host names which are part of the cluster and you will not give the host name instead you will give the VIP name let's say you have a four node cluster you would have four host names for IP addresses which are managed by the operating system but apart from that when you create the cluster you will give four VIPs and for VIP names or VIP host names which will be associated with all the four nodes the host name and we address is managed by the operating system whereas the VIP and the VIP name are managed by the cluster we're thereby whenever a node goes down the VIP will failover to another node and it will still respond but please note the VIP will not take new connection requests when it has failed over it is only going to tell back to the application that that VIP is down so in your client you would list all the VIPs so that when a client wants to connect it can look at any one of the VIPs and get connected so let's say I have for VIPs mentioned in my connect service name in my application or in my clinic string when a connection is made it will try with the first VIP if it could connect it gets connected if not it will try the second if not it will try the third so that is how in an RAC environment VIPs come into play there by the application need not necessarily know which nodes are up the process of connection itself will take care of connect time failover if node one has failed the VIP on node one will have failed over to area one of the remaining nodes and when a connection request comes it will immediately tell the client hey I am not available please try with some other node this is the underlying idea behind which database connectivity was established prior to 11g release 2 but it is in Levendi release 2 they brought about scan and two under scan the bots can we need to understand one more aspect called as server pools which we will understand in the next video [Music]

Channel: Ramkumar Swaminathan

Views: 45,785

Keywords: Oracle, Oracle SCAN, Oracle VIP, VIP in Oracle RAC, VIP and VIPNAME, why use Virtual IP in Oracle RAC, Single Client Access Name, Oracle Database, Oracle Database - RAC, Oracle Training, Oracle RAC Training, Oracle RAC Tutorial, Oracle RAC Concepts

Id: eOBM4Xu0Cic

Length: 4min 8sec (248 seconds)

Published: Wed Mar 14 2018