Saturday, July 16, 2011

Oracle 11g Rel 2: SCAN (Single Client Access Name)

Hi Friends,

Sometime back I have configured few Oracle 11g Rel 2 RAC database on Linux 5 operating system and here I would like to share some of the things I am aware of about SCAN.

Single Client Access Name
The single client access name (SCAN) is the address used by client connecting to the cluster. The SCAN is a fully qualified domain name (host name + domain) registered to n numbers of IP addresses.

I haven't used GNS so the SCAN needs to be defined in the DNS to resolve to all the addresses assigned to that name and it needs to be done before we start the installation of Oracle Grid Infrastructure. The SCAN and the associated IP addresses provide a stable name for clients to use for connections, independent of the nodes that make up the cluster.

SCAN is functioning like a cluster alias so application/end user never requires updated address of the server to connect either in the condition if some nodes are failed in the cluster.

During installation, listener are created on each node for the SCAN IP addresses and Oracle clusterware routes application/end user requests to the cluster SCAN to the least loaded instance providing the service.

Hope this topic will help you out,

Cheers!!!!

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