Oracle Clusterware Hardware Concepts and Requirements

A cluster consists of one or more servers. Access to an external network is the same for a server in a cluster (also known as a cluster member or node) as for a standalone server. However, a server that is part of a cluster, otherwise known as a node or a cluster member, requires a second network. This second network is referred to as the interconnect. For this reason, cluster member nodes require at least two network interface cards: one for a public network and one for a private network. The interconnect network is a private network using a switch (or multiple switches) that only the nodes in the cluster can access.^Foot 1

Cluster size is determined by the requirements of the workload running on the cluster and the number of nodes that you have configured in the cluster. If you are implementing a cluster for high availability, then configure redundancy for all of the components of the infrastructure as follows:

• At least two network interfaces for the public network, bonded to provide one address

• At least two network interfaces for the private interconnect network

The cluster requires cluster-aware storage^Foot 2 that is connected to each server in the cluster. This may also be referred to as a multihost device. Oracle Clusterware supports Network File Systems (NFSs), iSCSI, Direct Attached Storage (DAS), Storage Area Network (SAN) storage, and Network Attached Storage (NAS).

To provide redundancy for storage, generally provide at least two connections from each server to the cluster-aware storage. There may be more connections depending on your I/O requirements. It is important to consider the I/O requirements of the entire cluster when choosing your storage subsystem.

Most servers have at least one local disk that is internal to the server. Often, this disk is used for the operating system binaries; you can also use this disk for the Oracle software binaries. The benefit of each server having its own copy of the Oracle binaries is that it increases high availability, so that corruption of one binary does not affect all of the nodes in the cluster simultaneously. It also allows rolling upgrades, which reduce downtime.