Cooling fans, cooling air flow, and minimum clearance
The FortiGate-7040E chassis contains three hot swappable cooling fan trays installed in the back of the chassis. Each fan tray includes two fans that operate together. The fan tray includes two LEDs, one for each fan. When these LEDs are green both fans are operating normally. If one of the LEDs turns red or goes off, that fan is not working and the fan tray should be replaced.
During normal chassis operation, all three fan trays are active and the fan speed is controlled by the SMM. If a single fan tray fails, the SMM sends a warning message and the SMM front panel fan LEDs indicate that a fan tray has failed. The SMM maintains sufficient cooling by running the still operating fans at full speed to make up the airflow loss caused by the failed fan tray. The failed fan tray should be replaced as soon as possible.
If a second fan tray fails, the chassis can continue to operate but the chassis may experience high temperature warnings. Maintaining a lower ambient temperature can reduce the chance for overheating.
Fan trays are hot swappable. You can replace a failed fan tray while the chassis is operating. To replace a fan tray, unscrew the four retention screws and use the handles to pull the fan tray out of the chassis. Then apply the fan outlet cover to the outlet grill of the new fan tray. Install the new fan tray by sliding it into place. As you slide the new fan into place it will power up and the fan outlet cover will fall off of the fan tray. Tighten the retention screws.
The other fan trays will continue to operate and cool the chassis as a fan tray is being removed and replaced. However an open fan tray slot will result in less air flow through the chassis so do not delay installing the replacement fan tray.
The FortiGate-7040E System Management Module (SMM) monitors the internal temperature of the chassis and adjusts the operating speed of the cooling fans as required. When the chassis is first powered on, all cooling fans run at full speed. Once the SMM is up and running, it reduces cooling fan speeds to maintain an optimum temperature in the chassis. If the SMM is not installed or is not operating correctly, the fans always operate at full speed.
During normal operation, all fan trays are active. If cooling requirements increase, the fan speed will increase.
Cooling fan tray and outlet cover
Cooling air flow and required minimum air flow clearance
When installing the chassis, make sure there is enough clearance for effective cooling air flow. The following diagram shows the cooling air flow through the chassis and the locations of fan trays. Make sure the cooling air intake and warm air exhaust openings are not blocked by cables or rack construction because this could result in cooling performance reduction and possible overheating and component damage.
Most cool air enters the chassis through the chassis front panel and all warm air exhausts out the back. For optimal cooling allow 100 mm of clearance at the front and back of the chassis and 50 mm of clearance at the sides. Under these conditions 80% of cooling air comes from the front panel air intake and 20% from the left and right side panels and 100% exits out the back. Side clearance is optional and chassis cooling will be sufficient if no side clearance is available.
FortiGate-7040E cooling air flow and minimum air flow clearance (chassis side view)
