Nodes

A SAN Volume Controller node is a single processing unit within a SAN Volume Controller cluster.

For redundancy, nodes are deployed in pairs to make up a cluster. A cluster 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.

At any one time, a single node in the cluster manages configuration activity. This configuration node manages a cache of the configuration information that describes the cluster configuration and provides a focal point for configuration commands. If the configuration node fails, another node in the cluster takes over its responsibilities.

Table 1 describes the operational states of a node.

Table 1. Node state
State	Description
Adding	The node was added to the cluster but is not yet synchronized with the cluster state (see Note). The node state changes to Online after synchronization is complete.
Deleting	The node is in the process of being deleted from the cluster.
Online	The node is operational, assigned to a cluster, and has access to the fibre-channel SAN fabric.
Offline	The node is not operational. The node was assigned to a cluster but is not available on the fibre-channel SAN fabric. Run the Directed Maintenance Procedures to determine the problem.
Pending	The node is transitioning between states and, in a few seconds, will move to one of the other states.
Note: A node can stay in the Adding state for a long time. You should wait for at least 30 minutes before taking further action, but if after 30 minutes, the node state is still Adding, you can delete the node and add it again. If the node that has been added is at a lower code level than the rest of the cluster, the node is upgraded to the cluster code level, which can take up to 20 minutes. During this time, the node is shown as adding.