Using the Cluster Interconnect for Data Service Traffic

A cluster must have multiple network connections between nodes, forming the cluster interconnect. Sun Cluster software uses multiple interconnects to achieve the following goals:

• Ensure high availability

• Improve performance

For internal traffic such as file system data or scalable services data, messages are striped across all available interconnects in a round-robin fashion. The cluster interconnect is also available to applications, for highly available communication between nodes. For example, a distributed application might have components running on different nodes that need to communicate. By using the cluster interconnect rather than the public transport, these connections can withstand the failure of an individual link.

To use the cluster interconnect for communication between nodes, an application must use the private hostnames that you configured during the Sun Cluster installation. For example, if the private hostname for node 1 is clusternode1-priv, use that name to communicate with node 1 over the cluster interconnect. TCP sockets that are opened by using this name are routed over the cluster interconnect and can be transparently rerouted if the network fails.

Because you can configure the private hostnames during your Sun Cluster installation, the cluster interconnect uses any name you choose at that time. To determine the actual name, use the scha_cluster_get(3HA) command with the scha_privatelink_hostname_node argument.

Both application communication and internal clustering communication are striped over all interconnects. Because applications share the cluster interconnect with internal clustering traffic, the bandwidth available to applications depends on the bandwidth used by other clustering traffic. If a failure occurs, internal traffic and application traffic will stripe over all available interconnects.

Each node is also assigned a fixed pernode address. This pernode address is plumbed on the clprivnet driver. The IP address maps to the private hostname for the node: clusternode1-priv. For information about the Sun Cluster private network driver, see the clprivnet(7) man page.

If your application requires consistent IP addresses at all points, configure the application to bind to the pernode address on both the client and the server. All connections appear then to originate from and return to the pernode address.