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Sun Network QDR InfiniBand Gateway Switch Service Manual for Firmware Version 2.1 • March 2013
When a fan speed is too high, it is an indication of the condition of the fan, which if
gone unchecked can be detrimental to the operation of the gateway. A too-high fan
speed can be caused by:
■
Internal failure
– To regulate their speed, the fans use hall-effect sensors in an
internal feedback loop. If the sensor fails, the feedback loop opens, and the motor
overspeeds uncontrollably.
■
Other fan failure
– The algorithm used by the management controller
compensates for a fan failure by increasing the speed of the remaining functional
fans.
■
Fan obstruction
– If the fan intake is blocked, load on the fan is reduced, and the
fan overspeeds.
■
Temperatures too high
– If any component temperatures are too high, the fans
spin faster.
■
Supply voltage too high
– If the voltage at sensor target
/SYS/MB/V_12V
is too
high, the fans spin faster.
If a fan overspeeds for an extended time, it will fail. Consequently, insufficient
cooling air will be provided and the gateway will overheat.
When a fan speed is too low, it also is an indication of the condition of the fan, which
directly affects the operation of the gateway. A too-low fan speed can be caused by:
■
Coil failure
– The fan motor uses alternating electromagnetic fields to spin the fan
impeller. Depending upon the fan motor design, if the coil that creates a magnetic
field fails, the fan might spin much slower, or not at all.
■
Controller failure
– The controller alternates the electromagnet fields to spin the
fan impeller. If the controller fails, the fan might not spin at all.
■
Bearing failure
– The fan impeller is balanced on a bearing around which it spins.
The bearing is lubricated with an oil. If the bearing fails or the lubricant degrades,
the fan speed is reduced greatly.
■
Supply voltage too low
– If the voltage at sensor target
/SYS/MB/V_12V
is too
low, the fans spin slower.
If the fans speed is too low, insufficient cooling air will be provided and the gateway
will overheat.
When fan speeds are out of range, the suggested action is to replace any fan that is
not operating properly. See
“Servicing Fans” on page 55
. If new fans do not resolve
the problem, then replace the gateway.
Related Information
■
“Evaluate a Speed Sensor” on page 26
■
“Speed Sensor Values” on page 27
