An cefcFanTrayStatusTable entry lists the operational
status information for the ENTITY-MIB entPhysicalTable
entry which is identified by the value of entPhysicalIndex.
The value of entPhysicalClass for the identified entry will
be 'fan', and the represented physical entity will be
either: one physical fan, or a single physical 'fan tray'
which is a manufactured (inseparable in the field)
combination of multiple fans.
Entries are created by the agent at system power-up or
fan or fan tray insertion. Entries are deleted
by the agent at the fan or fan tray removal.