![](/images/new-backgrounds/1196610/19661075x1.webp)
Note: There are no parallel or serial ports on the x440. For serial connections, use the USB to Serial Adapter, part number 10K3661, as described in 3.2.4, “Serial connections” on page 83.
With the addition of an
Note: Currently, only one
1.9 Redundancy
The x440 has the following redundancy features to maintain high availability:
Four
With four
The other two fans are located just behind the power supplies and provide cooling for the I/O devices. Similar to the SMP Expansion Module fans, these fans will speed up in the event that one should fail to compensate for the reduction in air flow. In general, failed fans should be replaced within 24 hours following failure.
Important: Due to airflow requirements, fans should not be removed for longer than two minutes. The fan compartments need to be fully populated even if the fan is defective. Therefore, remove a defective fan only when a new fan is available for immediate replacement.
Two
Note: For large configurations, redundancy is achieved only when connected to a 220 V power supply. See 3.8, “Power considerations” on page 103 for details.