server shutdowns when internal temperatures exceed specification. Use cable ties and other wiring practices
to keep the rear of the chassis unobstructed as shown in the “after“illustration.
Figure 1: Cable Management
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Before After
Airflow through the chassis is from front to back. Air enters the chassis through the blade servers and power
supply grills at the front of the chassis and exits through the fan modules on the back of the chassis. Toensure
proper airflow,follow these guidelines:
•Maintain ambient airflow throughout the data center to ensure normal operation.
•Consider the heat dissipation of all equipment when determining air-conditioning requirements. Do not
allow the exhaust of one system to be the intake for another system.
•When evaluating airflow requirements, take into consideration that the hot air generated by equipment
at the bottom of the rack can be drawn in the intake of the equipment above.
•Make sure that the exhaust at the rear of the chassis is unobstructed for at least 24 in. (61 cm). This
includes obstruction due to messy cabling practices.
•Some bladeservers ship withinternal shrouds that are placed over the DIMMs and CPUs. They are used
to channel airflow to where it is needed the most. If a shroud can be used a given model, it should be
used.
•If an enclosed rack is used, the front door must be 65 percent perforated to ensure adequate airflow to
the servers.
Cisco UCS 5108 Server Chassis Installation Guide
OL-20035-05 3
Installation
Airflow Considerations