Compaq ProLiant 8000 Compaq ProLiant 8000 Server Technology - Page 14

TC000603TB TECHNOLOGY BRIEF (cont.) ... The server also has two hot-plug fans for the I/O board in the upper section of the server (Figure 7). Only one operating fan is needed to cool the I/O board. The other fan provides redundancy. If the operating fan should fail, the other fan would start automatically and continue cooling the I/O board. When the failed fan is replaced, redundancy is restored. Hot-Plug LEDs Figure 7: Hot-plug fans for the I/O section in the ProLiant 8000 server. The fan control logic operates independently from the system processor and OS. Regardless of which OS is running or its condition, the fan control logic and the server temperature monitoring circuitry work together to cool the server effectively. The fans have two speeds: normal and high. Under typical operating conditions, the normal fan speed is sufficient to cool up to 8 processors, 21 hard disk drives, and 11 I/O expansion boards. As a precaution against increases in ambient air or localized internal temperatures, Compaq established three thermal trip points, as shown in Figure 8. If the first thermal trip point is reached, the fans adjust automatically to high speed to increase cooling. Users can select whether to enable a server response to the second thermal trip point. When enabled, if the internal air temperature exceeds the second trip point, the OS initiates a controlled shutdown of the server. Simultaneously, a warning message is sent to the Integrated Management Display (IMD) and Compaq Insight Manager. The server restarts automatically when it has cooled sufficiently. Finally, in the unlikely event server temperature continues to rise, a third trip point shuts down the power supplies to protect critical components from overheating. The server restarts automatically when it has cooled sufficiently. 14