Friday, 18 May 2012

Issues in Service Registration to SCAN listener

Scneario

In a 3 node RAC/Cluster environment, one node (in our case node 2) crashed resulting in relocating the SCAN listener to another available node. However 2 out of 3 SCAN listener shows all the services registered in it except the last one which got relocated.

Hence the client connectivity intermittently experiences ORA-12514 error. i.e. Service not registered/unknown

Cause

Failed over SCAN listener hasn't got all the services registered in it hence whenever a client connection comes to this scan listener it was unable to process/redirect to the correct instance.

Solution

Simply de-register all the services from the remote/scan listener and re-register the same.
This can be achieved using the below simple script which helped us from avoiding a big extended outage.

deregister =>    ALTER SYSTEM SET REMOTE_LISTENER='';
Re-register => ALTER SYSTEM SET REMOTE_LISTENER='plocdb14:50000';
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