SCAN KeyPoints
$ /usr/sbin/nslookup rac-scan.example.com
$GRID_HOME/bin/srvctl config scan
$GRID_HOME/bin/srvctl config scan_listener
$ SRVCTL STATUS SCAN_LISTENER
$ lsnrctl services LISTENER_SCAN2
using EZConnect : *.REMOTE_LISTENER=rac-scan.example.com:25000
The keyword REMOTE SERVER, indicating that the LISTENER_SCAN2 listener will redirect the connection requests to the rac2 node VIP listener, thereby forwarding the connection to the RAC2 instance.
The lsnrctl services command output of a VIP listener will print services as LOCAL SERVER
keyword, indicating that the VIP listener will handle the connection for that service.
The local_listener parameter should refer to the VIP listener running on the
local node, and the remote_listener parameter should refer to the SCAN listeners using EZConnect syntax specifying the DNS alias of the SCAN IP address and port number
The initialization parameter remote_listener is set to the TNS alias of SCAN listener or EZConnect syntax using the SCAN IP address and port number.
SCAN IP is a new “layer” network (oracle) with high availability that allows you to change the characteristics of your cluster (i.e add/remove nodes) without the need to make configuration changes in their clients “Grid concept”.
The IP SCAN and VIP have different goals, therefore working together :
The VIP IP provides high availability at the level of the Cluster.
The SCAN IP provides high availability at the level of the Clients.
clusterclouds 