Oracle Single Client Access Name (SCAN) How to

Single Client Access Name (SCAN) is an Oracle Real Application Clusters (Oracle RAC) feature that provides a single name for clients to access Oracle Databases running in a cluster.The benefit  is that the client’s connect information does not need to change if you add or remove nodes or databases in the cluster.

In Oracle RAC 11gR2 or higher there are two listeners: traditional and scan listener. The management of both listeners should be done via srvctl command under Grid Infrastructure Home.

Traditional listener status:

# Set Environment to Grid Infrastructure Home [oracle@rac1 ~]$ . oraenv ORACLE_SID = [+ASM1] ? +ASM1 The Oracle base remains unchanged with value /u01/app/oracle # Listener Status [oracle@rac1 ~]$ srvctl status listener Listener LISTENER is enabled Listener LISTENER is running on node(s): rac2,rac1

Traditional listener port number:

[oracle@rac1 admin]$ srvctl config listener Name: LISTENER Network: 1, Owner: oracle Home: <CRS home> End points: TCP:1521

Stop traditional listener:

# Stop listener on node rac1 [oracle@rac1 ~]$ srvctl stop listener -n rac1 # Check status [oracle@rac1 ~]$ srvctl status listener Listener LISTENER is enabled Listener LISTENER is running on node(s): rac2

Start traditional listener:

# Start listener on node rac1 [oracle@rac1 ~]$ srvctl start listener -n rac1 # Check status [oracle@rac1 ~]$ srvctl status listener Listener LISTENER is enabled Listener LISTENER is running on node(s): rac2,rac1

SCAN listener status:

# Set Environment to Grid Infrastructure Home [oracle@rac1 ~]$ . oraenv ORACLE_SID = [+ASM1] ? +ASM1 The Oracle base remains unchanged with value /u01/app/oracle # SCAN Listener Status [oracle@rac1 ~]$ srvctl status scan_listener SCAN Listener LISTENER_SCAN1 is enabled SCAN listener LISTENER_SCAN1 is running on node rac2 SCAN Listener LISTENER_SCAN2 is enabled SCAN listener LISTENER_SCAN2 is running on node rac1 SCAN Listener LISTENER_SCAN3 is enabled SCAN listener LISTENER_SCAN3 is running on node rac1

Scan listener port number:

[oracle@rac1 admin]$ srvctl config scan_listener SCAN Listener LISTENER_SCAN1 exists. Port: TCP:1521 SCAN Listener LISTENER_SCAN2 exists. Port: TCP:1521 SCAN Listener LISTENER_SCAN3 exists. Port: TCP:1521

Stop SCAN listener:

# Stop SCAN Listener [oracle@rac1 ~]$ srvctl stop scan_listener

Start SCAN listener:

# Start SCAN Listener [oracle@rac1 ~]$ srvctl start scan_listener

Disable SCAN listener from automaticly start on the boot of the server:

# Disable SCAN Listener [oracle@rac1 ~]$ srvctl disable scan_listener # SCAN Listener Status [oracle@rac1 ~]$ srvctl status scan_listener SCAN Listener LISTENER_SCAN1 is disabled SCAN listener LISTENER_SCAN1 is running on node rac2 SCAN Listener LISTENER_SCAN2 is disabled SCAN listener LISTENER_SCAN2 is running on node rac1 SCAN Listener LISTENER_SCAN3 is disabled SCAN listener LISTENER_SCAN3 is running on node rac1

For more information see:

Real Application Clusters Installation Guide

I hope this helps.

Please feel free to leave your questions or suggest improvements to this section.