HP ProLiant BL660c HP BladeSystem c-Class architecture - Page 17

Figure 11. Different topologies require different emphasis settings Server blade-1 a DEV-1 Midplane b PCB Switch-1 PCB c Switch e Device Server blade-4 a d DEV-1 Onboard Administrator Signal midplane provides reliability Finally, to provide high reliability, the NonStop signal midplane is designed as a completely passive board, meaning that it has no active components along the high-speed signal paths. The PCB consists primarily of traces and connectors. While there are a few components on the PCB, they are limited to passive devices that are extremely unlikely to fail. The only active device is an Electrically Erasable Programmable Read-Only Memory (EEPROM), which the Onboard Administrator uses to acquire information such as the midplane serial number. If this device were to fail, it would not affect the signaling functionality of the NonStop signal midplane. The NonStop signal midplane incorporates best design practices and is based on the same type of midplane used for decades in high-availability solutions such as the HP NonStop S-series, core networking switches from Cisco, Juniper Networks and core SAN switches from Cisco and Brocade. HP engineers have estimated that the mean time between failure (MTBF) for the signal midplane is in the hundreds of years. 17