S-Series Reports Temperature as being "hot"

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Article ID: 13189 


Syslog ('show logging buffer') or Fault Log ('show support') report that the environment is hot.

For example:

System[3]Environmental temperature is normal.
System[3]Environmental temperature is hot.
System[3]Environmental temperature very hot.   Shutting down in +5c
System[3]Environmental temperature very hot.   Shutting down

Any of the "hot" messages may be an indication of inadequate equipment ventilation, or a board running hot for any reason.

The reported condition may be investigated by viewing the temperature readings local to the chassis fans, and local to each slot module or standalone system:
  • The fan temperature will typically read 2 to 4 C higher than the ambient temperature immediately outside the chassis air intake, due to heat input from the running system. This is an important benchmark. Cooler ambient air will lead to a cooler-running system.
    The fan temperature should remain lower than 44 C.

  • The board temperature is taken closer to the heat-generating components.
    A board temperature transitioning back down to 65 C triggers the "normal" message.
    A board temperature of 70 C triggers the "hot" message.
    A board temperature of 80 C triggers the "very hot" message.
    A board temperature of 85 C causes the board to shut itself off, and remain off, until a reseat or full power recycle.

    Note: If a system's temperature rises sufficiently quickly - due to some combination of hot environment, blocked vents, and/or failed fans - then it is possible that only some (or none) of the "hot"/"very hot" messaging will be issued before the board shuts itself off.

These local temperature readings are displayed in the output of a 'show system hardware' command, with this example taken from a system located in an improperly vented area:
  • For chassis-based fans, look within the "CHASSIS HARDWARE INFORMATION" section-

        Chassis Fan 1 Temperature:  29.000  C
        Chassis Fan 2 Temperature:  28.000  C

  • For slot modules or standalone systems, look within the "SLOT HARDWARE INFORMATION" section, reported by slot-

        SLOT 1
            . . .
               LM75                                                      53.000  C

Heat in general degrades the lifetime of many electronic components. To achieve maximum component life, wiring closets and data centers should try to keep the equipment's ambient air temperature as close to standard room temperature as possible. In North America this is considered to be 21-25 C (70-75 F).

If you see a fan temperature of 44 C or higher, or a board temperature of 70 C or higher, please contact the GTAC for assistance.
See also: 13226 and 13261.
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Posted 4 years ago

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