SCAN listeners are remote listeners and act as a forefront of connection management, applications connect to SCAN listeners.
and SCAN listeners act as a conduit mechanism to forward connections to an instance that can provide better quality of service.
When a client submits a connection request, the SCAN listener listening on a SCAN IP address
and the SCAN port are contacted on the client’s behalf. Because all services on the cluster are
registered with the SCAN listener, the SCAN listener replies with the address of the local
listener on the least-loaded node where the service is currently being offered.
During installation, listeners are created on nodes for the SCAN IP addresses.
To check the status of SCAN listener use the command lsnrctl status < scan listener name>
For example:
grid@dbsrv:/u01/app/12.1.0/grid/network/admin$ lsnrctl status LISTENER_SCAN1 LSNRCTL for Solaris: Version 12.1.0.2.0 - Production on 05-SEP-2022 16:58:18 Copyright (c) 1991, 2014, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1))) STATUS of the LISTENER ------------------------ Alias LISTENER_SCAN1 Version TNSLSNR for Solaris: Version 12.1.0.2.0 - Production Start Date 01-SEP-2022 03:47:55 Uptime 4 days 13 hr. 10 min. 23 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/12.1.0/grid/network/admin/listener.ora Listener Log File /u01/app/grid/diag/tnslsnr/wgpdbsrv1/listener_scan1/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.02.10.10)(PORT=1521))) Services Summary... Service "dbprod" has 1 instance(s). Instance "dbprod1", status READY, has 2 handler(s) for this service... Service "dbprodXDB" has 1 instance(s). Instance "dbprod1", status READY, has 1 handler(s) for this service... The command completed successfully
And to check the services of the SCAN listener use lsnrctl services < scan listerner name>
Example:
grid@dbsrv:/u01/app/12.1.0/grid/network/admin$ lsnrctl services LISTENER_SCAN1 LSNRCTL for Solaris: Version 12.1.0.2.0 - Production on 05-SEP-2022 17:01:57 Copyright (c) 1991, 2014, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1))) Services Summary... Service "dbprod" has 1 instance(s). Instance "dbprod1", status READY, has 2 handler(s) for this service... Handler(s): "DEDICATED" established:1262 refused:0 state:ready REMOTE SERVER (ADDRESS=(PROTOCOL=TCP)(HOST=10.02.10.44)(PORT=1521)) "DEDICATED" established:1251 refused:0 state:ready REMOTE SERVER (ADDRESS=(PROTOCOL=TCP)(HOST=10.02.10.44)(PORT=1521)) Service "dbprodXDB" has 1 instance(s). Instance "dbprod1", status READY, has 1 handler(s) for this service... Handler(s): "D000" established:0 refused:0 current:0 max:1022 state:ready DISPATCHER <machine: dbsrv, pid: 7778> (ADDRESS=(PROTOCOL=tcp)(HOST=dbsrv.abc.com)(PORT=45000)) The command completed successfully