The FortiGate-7121F chassis contains six hot swappable cooling fan trays installed in the back of the chassis. Each fan tray includes two fans that operate together. When the fan tray LED is green, both fans are operating normally. If the LED turns red or goes off, one or both of the fans is not working and the fan tray should be replaced.
During normal chassis operation, all six fan trays are active and the fan speed is controlled by the active 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 of 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.
Install a replacement fan tray by sliding it into place in the empty slot and tightening the retention screws. As you slide the new fan into place it will power up and the fan tray LED will light.
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 active 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 active SMM is up and running, it reduces cooling fan speeds to maintain an optimum temperature in the chassis. If an SMM is not available 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.