RAC 11.2: Reconfigure SCAN Addresses

At install time there is the possibility to install RAC with one SCAN address specified in /etc/hosts file. If after installation, SCAN IPs are available through DNS (Oracle recomend 3 ip addresses to SCAN name), then the SCAN must be reconfigured 

[grid@oracle-node-2 ~]$ srvctl stop scan_listener

[grid@oracle-node-2 ~]$ srvctl stop scan

[grid@oracle-node-1 ~]$ more /etc/hosts

...... 

SCAN IPs

172.18.16.68    oracle-rac-scan.oracle.com      oracle-rac-scan

#172.18.16.69    oracle-rac-scan.oracle.com     oracle-rac-scan

#172.18.16.70    oracle-rac-scan.oracle.com     oracle-rac-scan

........ 

[root@oracle-node-1 ~]$ vi /etc/hosts

SCAN IPs

#172.18.16.68    oracle-rac-scan.oracle.com     oracle-rac-scan

[grid@oracle-node-1 ~]$ srvctl config scan

SCAN name: oracle-rac-scan, Network: 1/172.18.16.0/255.255.254.0/eth0

SCAN VIP name: scan1, IP: /oracle-rac-scan/172.18.16.68

[root@oracle-node-1 ~]# cd /u01/app/11.2.0/grid/bin/

[root@oracle-node-1 bin]# ./srvctl modify scan -n oracle-rac-scan

[root@oracle-node-1 bin]# ./srvctl config scan

SCAN name: oracle-rac-scan, Network: 1/172.18.20.0/255.255.254.0/eth0

SCAN VIP name: scan1, IP: /oracle-rac-scan/172.18.20.69

SCAN VIP name: scan2, IP: /oracle-rac-scan/172.18.20.70

SCAN VIP name: scan3, IP: /oracle-rac-scan/172.18.20.68

[root@oracle-node-1 bin]# ./srvctl modify scan_listener -u

[root@oracle-node-1 bin]# ./srvctl start scan

[root@oracle-node-1 bin]# ./srvctl start scan_listener

[root@oracle-node-1 bin]# ./srvctl status scan_listener

SCAN Listener LISTENER_SCAN1 is enabled

SCAN listener LISTENER_SCAN1 is running on node oracle-node-2

SCAN Listener LISTENER_SCAN2 is enabled

SCAN listener LISTENER_SCAN2 is running on node oracle-node-1

SCAN Listener LISTENER_SCAN3 is enabled

SCAN listener LISTENER_SCAN3 is running on node oracle-node-1

[root@oracle-node-1 bin]# ./srvctl status scan

SCAN VIP scan1 is enabled

SCAN VIP scan1 is running on node oracle-node-2

SCAN VIP scan2 is enabled

SCAN VIP scan2 is running on node oracle-node-1

SCAN VIP scan3 is enabled

SCAN VIP scan3 is running on node oracle-node-1

[root@oracle-node-1 bin]#

From Oracle documentation:

srvctl modify scan -n scan_name

Modifies the SCAN VIP configuration to the match that of another SCAN VIP you specify with scan_name. If scan_name currently resolves to more IP addresses than when it was initially configured, then the utility creates new Oracle Clusterware resources for those additional IP addresses. If scan_name currently resolves to fewer IP addresses, then the utility removes Oracle Clusterware resources for SCAN VIP addresses with numerically higher ordinal numbers until the remaining SCAN VIP resources match the number of IP addresses to which scan_name resolves.