HP Surestore E Tape Library Model 6/60 HP SureStore E Tape Library Models 2/20 - Page 212

NOTE Introduction to Fibre Channel Fibre Channel Technology During normal operations, device addresses do not change. Fibre Channel addresses can only change when device communications are disrupted. Consequently, system software does not need to spend extra time during normal operations to keep track of device addresses. All Fibre Channel devices are identified using their WWN. The WWN is used by system software to locate devices independent of how they are connected to the system so that the software does not need to be reconfigured every time the system is reconfigured. Also, being able to track devices helps prevent losing or damaging data by accidentally accessing the wrong device in the system. This is a very important requirement for the development of the SAN (Storage Area Network) systems. Common Problems with Fibre Channel Fibre Channel accommodates many protocols and physical interfaces, but problems can occur with the following: • Physical connections • Laser power control systems • Error recovery Physical Connections Physical connection problems arise from connecting devices with different types of cables, poor connections, damaged cables, or damaged connectors. ANSI controls the cable specification. The maximum distance between devices depends on the type of cable and desired data transmission speed. As with all electrical media, Fibre Channel copper media can radiate RF interferences and can be affected by external RF noises. Because of the distance limitations and noise problems, copper media is only recommended for use inside a cabinet or rack. Use the optical cable(s) included with the library to connect the library to the Fibre Channel loop (host, hub, or switch). C- 14 Appendix C