System Fan Configuration; N+1 Hot-Swap Power Supply Configuration; Cover Interlock - Compaq AlphaServer DS20E Reference Manual

1-14 DS20E Reference Guide

System Fan Configuration

N+1 Hot-Swap Power Supply Configuration

Cover Interlock

Part Number: ER-K8F6W-UA .A01 File Name: b-ch1 System Overview.doc Last Saved On: 10/4/99 1:23 PM
N+1 Configuration
The system has two fans; for optimal cooling, both fans are running. If one of
the fans were to fail or were removed for servicing (hot-swapping), the system
will continue to function with the other fan running.
As system temperature rises, the fan speed increases to increase cooling. If the
system temperature rises above 50ºC (due to high system loads or high
ambient temperature), the system software will receive an I/O interrupt and the
system will shut down within 30 seconds.
Thermostatic System Fan Control
The fan control thermostat is located at
to drive the fans at their minimum speed in normal computer room
environments below 26 degrees C to keep noise levels low. At higher
temperatures, the fans run faster to provide more air flow.
As an ultimate backup, system shutdown will be initiated if the internal
temperature reaches 50-55ºC. Firmware or software sets this value.
The SFM enforces the system requirement to have two functional power
supplies in order to operate. Using the ≤ 30 second shutdown timer, the SFM
shuts down the system if the number of working power supplies ever falls
below two. In a three power supply configuration, a power supply may be
removed for servicing without interrupting system operation. An I/O interrupt
will be generated whenever the number of power supplies in operation
changes, and the status LEDs will indicate the change also.
The system does not operate with the system enclosure open. System power
cannot be turned on until the cover is closed. If the cover is opened while the
system is running, power will shut off immediately.
The cover connector is found on the SFM at J2, and
Compaq Confidential – Need to Know Required
Writer: Robert Young Project: DS20E Reference Guide Comments:
in Figure 1-5. The thermostat is set
in Figure 1-5.