It’s not a new phenomenon, Sun did it over a decade ago with the 4500 range of servers that vent hot air left to right rather than front to back but it doesn’t make it any easier to run a complex site when major vendors like Cisco continue to insist on breaking the front to back cooling convention.

Lots of data center managers started to get major problems with Sun 4500 servers falling over with overheating problems. Why? Well because they located them in nice neat lines in racks so the first 4500 took in cold air from the left and heated it, exhausting to the right where 4500 number 2 drew in hot air and heated it again only to be taken onto 4500 number 3 which started to shut down….

I have Stuart Hall at Arup to thank for this extremely useful advice on how to position and manage Cisco 6509 equipment in a data center.

Cisco System’s design much of their equipment with cable management in mind. On occasion the convenience of the connectivity of cables sees the vented areas of Cisco System’s equipment moved to unusual positions on the equipment cases.

The norm for data center equipment is for air to be provided at the front of the equipment and to be exhausted at the rear. It is sensible to design a datacenter’s infrastructure accordingly for this type of airflow delivery. 

It follows that careful provisions must be made for Cisco System’s equipment in order to accommodate it within a front-in-back-out data center environment. 

This document investigates the effectiveness of a Cooper B-line cabinet, equipped with Cooper B-Line add-on baffles and blanking plates, at directing air to and from the intakes of Cisco System’s 6509 equipment. Cisco System’s 6509 is a commonly used unit with particularly difficult air flow requirements.

Cooper B-Line produces a range of, simple, modular products for dividing the space within cabinets.

Blanking plates, fitted in the unused U-slots to the front and side, prevent air being supplied directly from the equipment’s own exhaust. Brushed strips to the sides (show installed to the front left and rear right) allow cables to pass through the baffles without allowing air to escape. Side U-slots are depth adjustable to allow for different types of equipment.

The Cooper B-line solution successfully allows the Cisco equipment to be housed and cooled in a datacenter applying a front-in back-out equipment cooling strategy.

The system is not specific to one particular model of equipment and therefore allows for greater flexibility. (I.e. the same components could be reused to house a completely different server at a later date if so required).

The principle employed by Cooper B-line is not novel and therefore similar products from other manufacturers may perform equally as effectively.

The diagram on the right shows two racks, the one on the left with blanking plates fitted, forcing airflow front to back, whilst the other shows an unblanked example.

Note the impact of uncontrolled airflow causing the upper switch to draw in hot air from the switch below.

The diagrams are created using Arup’s airflow visualization software which is a story in itself for a later article.