This seems fine.
Run the below command 4-5 times and ensure that SCAN is working in round-robin fashion.
Tried many times and nslookup command working fine.
If its working in "round-robin fashion" then I think, its absolutely fine.
You can certainly define your regular VIP's in the hosts file if you choose. But if you plan on letting your applications use the regular VIP's, then you should put them in DNS as well. If you plan on having your applications use the SCAN VIP's instead (which is a good idea), then the regular VIPs do not need to be in DNS.
As I informed earlier, I have defined 3 SCAN IPs in DNS server. Rest of the IPs (Public, Private, and Virtual) defined in the /etc/hosts file. When I pinging from client machine nslookup is working perfectly and this in round-robin. My doubt is whether this configuration is okay or not.
Your configuration is ok so long as your applications only connect through the SCAN Listeners. And there is little reason in 11gR2 or higher to do anything else.
However, if you need or desire to use the old listeners, then you will have to put the other VIP's in DNS as well.
Thanks Brian for sharing good information
We don't have DNS Server available.
We are only using single SCAN IP using /etc/hosts
We are using the Local VIP URL for access the database
Can you share your suggestion regarding in terms of performance for making fast connection instead of scan connection.
You should be good to go then.
The performance with a SCAN Listener should be no different (from the end user's perspective) than with the older listeners.
Q: Can you share your suggestion regarding in terms of performance for making fast connection instead of scan connection.
A: SCAN is basically used for Load Balancing purpose. You can set SCAN IP in /etc/hosts. However,
- Oracle strongly recommends that you do not configure SCAN VIP addresses in the hosts file. But if you use the hosts file to resolve SCAN name, you can have only one SCAN IP address.
- For high availability and scalability, Oracle recommends that you configure the SCAN to use DNS Round Robin resolution to three addresses.
Ref: Grid Infrastructure Single Client Access Name (SCAN) Explained (Doc ID 887522.1)
Local VIP direct align with the local Instance
LOCAL VIP ===> LOCAL LISTENER ===> DB ACCESS
SCAN VIP direct align with the either node LOCAL LISTENER
SCAN VIP ====> SCAN LISTENER ====> LOCAL LISTENER ====> DB ACCESS
Congrats !! Now check the failover status by running down nodes one by one, means just evict the one node and see failover is happening or not on second node.
RAC is primarily using for availability and this is the mail feature . If its working fine , then all is well .
Shivendra Narain Nirala