All nodes must be connected by the cluster interconnect through at least two redundant physically independent networks, or paths, to avoid a single point of failure. While two interconnects are required for redundancy, up to six can be used to spread traffic to avoid bottlenecks and improve redundancy and scalability. The Sun Cluster interconnect uses Fast Ethernet, Gigabit-Ethernet, InfiniBand, or the Scalable Coherent Interface (SCI, IEEE 1596-1992), enabling high-performance cluster-private communications.
In clustered environments, high-speed, low-latency interconnects and protocols for internode communications are essential. The SCI interconnect in Sun Cluster systems offers improved performance over typical network interface cards (NICs).
The RSM Reliable Datagram Transport (RSMRDT) driver consists of a driver that is built on top of the RSM API and a library that exports the RSMRDT-API interface. The driver provides enhanced Oracle Real Application Clusters performance. The driver also enhances load-balancing and high-availability (HA) functions by providing them directly inside the driver, making them available to the clients transparently.
The cluster interconnect consists of the following hardware components:
Adapters – The network interface cards that reside in each cluster node. A network adapter with multiple interfaces could become a single point of failure if the entire adapter fails.
Switches – The switches, also called junctions, that reside outside of the cluster nodes. Switches perform pass-through and switching functions to enable you to connect more than two nodes. In a two-node cluster, unless the adapter hardware requires switches, you do not need switches because the nodes can be directly connected to each other through redundant physical cables. Those redundant cables are connected to redundant adapters on each node. Configurations with three or more nodes require switches.
Cables – The physical connections that are placed between either two network adapters or an adapter and a switch.
Figure 3–4 shows how the three components are connected.