Nodes
Each node is a single processing unit within a system.
For redundancy, nodes are deployed in pairs to make up a system. A system can have one to four pairs of nodes. Each pair of nodes is known as an I/O group. Each node can be in only one I/O group. A maximum of four I/O groups each containing two nodes is supported.
Note: Both nodes in an I/O group must have the same amount of memory
installed.
At any one time, a single node in the system manages configuration activity. This configuration node manages a cache of the configuration information that describes the system configuration and provides a focal point for configuration commands. If the configuration node fails, another node in the system takes over its responsibilities.