Error Message

• Single client access name (SCAN) is the virtual hostname to provide for all clients connecting to the cluster (as opposed to the vip hostnames in 10g and 11gR1).
• SCANis a domain name registered to at least one and up to three IP addresses, either in the domain name service (DNS) or the Grid Naming Service (GNS).
• By default, the name used as the SCAN is also the name of the cluster and must be globally unique throughout your enterprise. The default value for the SCAN is based on the local node name. SCAN name must be at least one character long and no more than 15 characters in length, must be alphanumeric - cannot begin with a numeral and may contain hyphens (-). If you require a SCAN that is longer than15 characters, then select an Advanced installation.
• For installation to succeed, the SCAN must resolve to at least one address.
• SCANVIP addresses must be on the same subnet as virtual IP addresses and public IPaddresses.
• Oracle strongly recommends that you do not configure SCAN VIP addresses in the hosts file. If you use the hosts file to resolve SCANs, then you will only be able to resolve to one IP address and you will have only one SCAN address - be sure to provide a hosts file entry for each SCAN address in hosts file in same order.
• Ifhosts file is used to resolve SCAN hostname, you will receive ClusterVerification Utility failure at end of installation (see Note: 887471.1 for moredetails)
• For high availability and scalability, Oracle recommends that you configure the SCANto use DNS Round Robin resolution to three addresses.
• Because the SCAN is associated with the cluster as a whole, rather than to a particular node, the SCAN makes it possible to add or remove nodes from the cluster without needing to reconfigure clients. It also adds location independence for the databases, so that client configuration does not have to depend on which nodes are running a particular database.
• Client scan continue to access the cluster in the same way as with previous releases,but Oracle recommends that clients accessing the cluster use the SCAN. Clients using the SCAN can also access the cluster using EZCONNECT.
• GridInfrastructure will start local listener LISTENER on all nodes to listen to onlocal VIP, and SCAN listener LISTENER_SCAN1 (up to three cluster wide) to listen on SCAN VIP(s); 11gR2 database by default will set local_listener to local LISTENER, and remote_listener to SCANlistener.