3 Replies Latest reply: Nov 7, 2011 2:37 AM by Sebastian Solbach -Dba Community-Oracle RSS

    Should SCAN VIP and Listener jump among Nodes?

    thtsang
      Oracle (GI and DB): 11.2.0.3 SE
      OS: RHEL 5.6

      I remember when I first tried scan several years ago (most likely with 11.2.0.1 EE), the SCAN VIP and Listeners jumps from node to node whenever a DB connection was established.

      Recently, in a newly installed 2 node cluster running 11.2.0.3 SE, it seems the SCAN VIP and Listener stick to a single node unless during failover or requested with a command. As a result, a SCAN VIP and Listeners end up running on a single node after some failover testing.

      Which is the designed behaviour? I understand they can direct connection requests to DB instance on other node. Just want to know whether they are supposed to jump?
        • 1. Re: Should SCAN VIP and Listener jump among Nodes?
          Sebastian Solbach -Dba Community-Oracle
          Hi,

          I have not tried it myself, but if you look at the crs profile on how SCANs are defined, they are set to DISPERSION.
          # crsctl stat res ora.scan1.vip -p
          NAME=ora.scan1.vip
          TYPE=ora.scan_vip.type
          ...
          START_DEPENDENCIES=hard(ora.net1.network) dispersion:active(type:ora.scan_vip.type) pullup(ora.net1.network)
          ...
          So they should not/never run on the same node, since the dispersion policy tells them differently.

          However this dependency is checked at startup time, and not always during runtime. So if you do a lot of test, your szenario is possible.
          Have you tried waiting a while, if this resolves the issue?

          If they stay on the same node, I would open an SR, because then it does not follow the dispersion policy.

          Regards
          Sebastian
          • 2. Re: Should SCAN VIP and Listener jump among Nodes?
            thtsang
            It eventually redistributed to run on both nodes (we are running 2 node RAC). But the situation that all 3 SCAN IP running on the same node has persisted over 2 days.

            We have started and stopped DB instances after that. Can registration / deregistration cause them to jump around?

            Also, are they supposed to jump around after normal database connection?
            • 3. Re: Should SCAN VIP and Listener jump among Nodes?
              Sebastian Solbach -Dba Community-Oracle
              Hi,

              no SCANs will only move with clusterware up and down (they run from Grid Infrastruktur).
              Self registration of the database has no effect on the SCAN itself (other than that the SCAN knows the database).

              You can start and stop a SCAN VIP, that will have the effect that after the start the SCAN VIP will move to another server.

              Regards
              Sebastian