3 Replies Latest reply: Sep 2, 2013 9:15 AM by Pradeepcmst RSS

    How to failover SCAN VIP and SCAN Listener from one node to another?

    Sivaprasad S


      O.S :          HP-UX  B.11.31 U ia64

      RDBMS:   Oracle Database 11g Enterprise Edition Release - 64bit Production

      It is a 2 Node RAC.




      1. How to failover the SCAN VIP and SCAN LISTENER running on node 1 to node 2?
      2. What is the relation between standard LISTENER and SCAN LISTENER ?
      3. Why do we need LISTENER, when we have SCAN LISTENER ?
      4. When I tried with SRCVTL STOP LISTENER , I thought the SCAN LISTENER adn SCAN IP will failover, but it did not?
      5. Also please clarify if I use SRVCTL RELOCATE SCAN -i 1 -n Node1
        Actalluy I am trying that by moving the SCAN listeners so that when I do PSU 7 patching on 1 node, no incoming attempt to connect will spawn
        a process and thereby opening files in $ORACLE_HOME (which would prevent the patch from occurring)


      Please clarify my queries.


      Thanks,  Sivaprasad.S

        • 1. Re: How to failover SCAN VIP and SCAN Listener from one node to another?

          Hi Sivaprasad,


          1. The following link will help you for SCAN VIP and SCAN LISTENER failover from 1 node to another.




          2. The Standard LISTENER is specific for particular node for which it is running. It cannot be relocated as its specific for the node its running. SCAN listeners are not replacements for the node listeners.A new set of cluster processes called scan listeners will run on three nodes in a cluster (or all nodes if there are less than 3).  If you have more than three nodes, regardless of the number of nodes you have, there will be at most three scan listeners. So no relation for standard LISTENER and SCAN LISTENER.


          3. Hmmm. let me put it in easy way for this question. All the RAC services like, asm, db , services, nodeapps registers with this SCAN_LISTENER. So if any of these services (asm, db , services, nodeapps) got down/not running, the SCAN_LISTENER will know the down status, and if any client requests to access the node/service which is down, the SCAN_LISTENER will redirect the client request to the least loaded node. So here all these process will happen without the knowledge of client. And As usual the standard LISTENER looks only for incoming request to connect with the database. So we need both LISTENER and SCAN LISTENER.


          4. If you provide SRCVTL STOP LISTENER,  it stops the default listener on the specified node_name, or the listeners represented in a given list of listener names, that are registered with Oracle Clusterware on the given node. No failover will happen under this case.


          5. Yes you can relocate if you want to relocate the scan.



          Hope this helps!!



          Pradeep. V

          • 2. Re: How to failover SCAN VIP and SCAN Listener from one node to another?

            Your questions:

            1.     Failover occurs after a failure, You can't do it manually. Reboot a node and you will see it happen.

            2.     SCAN listeners redirect connect requests to node listeners.

            3.     They have different functions. SCAN listeners do redirection, node listeners spawn and bequeath sessions.

            4.     srvctl stop listener will have no effect on a SCAN listener or SCAN VIP.

            5.     The instructions with the patch set do not tell you to do this.

            • 3. Re: How to failover SCAN VIP and SCAN Listener from one node to another?

              Hi Sivaprasad,

              kindly mark the thread as closed if you are clear.




              Pradeep. V