title: Checks the FAN sensors on Dell PowerConnect Switches
agents: snmp
author: Chris Bowlby <cbowlby@tenthpowertech.com>
license: GPL
distribution: check_mk
description:
 This check monitors the various FAN sensors on a Dell PowerConnect switch that supports
 the DELL-VENDOR-MIB. It will monitor the state of the FAN itself, depending on the
 state returned by the FAN.

 If a switch has more then one FAN sensor, it will create a service for EACH sensor.
 However, if a switch has any FANS that are not connected up to the sensor suite, or
 there is an empty FAN bay, they will not be picked up by this check.

 A FAN that is running normally will return an OK nagios state. Any FAN that
 are in a warning or is not present (if it was previously present) will return a WARNING 
 nagios state. If a FAN is in a critical or is non-functional according to the sensor will 
 return a CRITICAL nagios state. Lastly, if a FAN is in a "shutdown" state, it will return
 an UNKNOWN nagios state.

 Currently, testing has been completed with the Dell PowerConnect 5448 and 5424 models,
 however the service check may work with other models.

perfdata: 
 Each FAN sensor uses a single variable value (0..1) representing 
 the state of the FAN itself. A 1 represents a normal "ON" state, where as
 a 0 represents any "OFF", which can mean warning, critical, shutdown, 
 not present (only if previously present), or not functioning. This is simply
 to chart the state of the FAN itself.

inventory:
 During the inventory phase of check_mk, it will create one or more service {Sensor fanX_unitX}
 entries, as long as the MIB defined above is supported on the switch.

example:
 If a switch has 3 FANS in the device, it will create 3 service entries titled:

 Sensor fan1_unit1
 Sensor fan2_unit1
 Sensor fan3_unit1

 The fanX value represents the selected FAN, where as the unitX values represents the sensor 
 assigned to the FAN. It is possible to have multiple sensors on a single FAN, though I have
 yet to see one.
