Power Supply Airflow and Switch Fan Module Airflow

The power supply module has its own fan for cooling the power supply, and each of the two switch fan modules has two fans for cooling the switch circuitry. The airflow direction of all three modules must agree in order to properly cool the installed SSA system. In rack mount configurations the best practice is to mount all devices with a common cool air side and a common exhaust (hot air) side.

On the SSA switch, two airflow directions are supported:

• The I/O port side to the power supply side
• The power supply side to the I/O port side

Note

The power supplies are ordered separately from the switch unit, and you must specify the airflow direction when you order them. Power supply airflow direction is fixed and cannot be changed manually. If the ordered power supply has an airflow direction that does not work for your rack configuration, you must order another power supply that has the correct airflow direction (see Power Supply Airflow Based on Model Number).

The SSA switch, as shipped from the factory, is set up for airflow direction from the I/O port side to the power supply side. If your installation requires that airflow direction be from the power supply side to the I/O port side, you must reverse the airflow of the switch fan module fans (see Reversing the Fan Module Airflow). Also, you must reverse the rack mount flanges (ears) (see Rack Mount Ear Positioning).

You can determine airflow direction of the switch fan modules by visually inspecting them for whether a white label or a fan blade is visible through the fan screen.

Before securing the SSA switch to the rack or installing the power supply into the SSA switch, unpack the power supply module (see Unpacking the Power Supplies) and visually verify that its airflow direction and that of the switch fan modules agree with the intended configuration as defined in Switch Fan Module Airflow Direction and Power Supply Airflow Based on Model Number.

Switch Fan Module Airflow Direction

Airflow Direction	Visual Indication
From I/O port side to power supply side	White label is visible on fan unit
From power supply side to I/O port side	Fan blade is visible on fan unit

The power supply airflow direction can also be verified using the power supply manufacturer‘s part number located on the power supply bottom label.

Power Supply Airflow Based on Model Number

Model Number	Mfg. Part Number	Airflow Direction
SSA-FB-AC-PS-A	DS460S-3-003	From power supply side to I/O port side
SSA-FB-AC-PS-B	DS460S-3-002	From I/O port side to power supply side