IBM SAN Volume Controller nodes are always installed in pairs, forming an I/O group. A  minimum of one pair and a maximum of four pairs of nodes constitute a clustered SAN  Volume Controller system. Many of the components that make up IBM SAN Volume  Controller nodes include LEDs that indicate the status and activity of that component. Figure 13-1 shows the rear view, ports, and indicator lights on the IBM SAN Volume  Controller node model 2145-SV1. The Fibre Channel (FC) or 10 Gbps Ethernet adapters are installed horizontally on the mid-  and right sides of the node. The 2145-SV1 can accommodate up to four quad-port 16-Gbps  FC cards, or one 4-port 10-gigabit Ethernet (GbE) adapter in a stand-alone configuration or in  combination with an FC card. Table 13-1 lists the meaning of port LEDs for an FC configuration. Two active USB connectors are available in the horizontal position. They have no numbers  and no indicators are associated with them. These ports can be used for initial cluster setup,  encryption key backup, and node status or log collection. Host interface cards USB ports Figure 13-1 Rear ports and indicators of IBM SAN Volume Controller model 2145-SV1 Table 13-1 Fibre Channel link LED statuses Chapter 13. Reliability, availability, and serviceability, and monitoring and troubleshooting  707 Port LED Color Meaning Link status Green Link is up, connection established. Speed Amber Link is not up or there is a speed fault.