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Is your cabling ruining your efficiency?

Cables degrade over time. Discover what you can do so won't steam up or error out.

While we all understand the importance of a quality infrastructure to support and carry data traffic, there are other areas in the data center where cabling may be hurting your environment. In particular, your cooling capabilities and the degradation of connections over time. The first is rapidly becoming a cost drain. Older cooling units and even the latest and greatest cooling units will suffer if they can not move air into the desired locations. The effect of abandoned cable under a data center floor is an air damn. To what extent the air is damned by the cable depends on the height of the floor, the amount of cabling under the floor and how strong the airflow is under the floor. The same can hold true for overhead ladder racks and cable trays. If the air system forces air down, it should be designed so that the air ducts are not directly positioned over any cable pathway obstruction. In the new hot and cold aisle arrangements, the cabling would be run and positioned in the hot aisles. This assures an unobstructed air pathway for the cold aisles.

The new version of the National Electrical Code (2005) calls for the removal of abandoned cable. In order for a cable not to be considered abandoned, it must be terminated at both ends or flagged for future use. While the rationale behind this is the fuel load in the event of a fire, it also makes sense when you look at your power consumption based on air handlers that have to work overtime. While this is a U.S. code, there are countries outside of the U.S. that use it as a guideline too. Historically, fire damage is about 95% smoke related and only 5% fire related, so removing a source of smoke is certainly of benefit.

Another key point is in TIA-942 "Telecommunications Infrastructure for Data Centers" which states that point-to-point cabling should not be used unless specified by the manufacturer. This would include bus based systems as well as point-to-point connections. There are two problems with point-to-point connections. First, they are generally specialty cables that are field terminated. Second, they are generally shoved below a raised floor when abandoned because the sheer amount of them makes them very hard to remove. It is also difficult to bring in other equipment due to the amount of cabling run haphazardly under the floor. While these cables may test OK at first, over time, the connections will degrade. Factory terminated cables are crimpled and terminated with exact pressure. Also termination to patch panels and/or punch down blocks offer better termination when done properly. A hand held crimping tool will provide varied terminations depending on who is doing the termination and how many cables have been terminated by that person as muscles tend to weaken. If the cables are not properly supported over the channel and near the termination points, the cable performance will degrade creating bit errors.

TIA-942 also goes a bit farther to state that horizontal and vertical cabling should be run accommodating growth so that you do not have to revisit these areas. This assures that the cabling will be run properly and that any patching would be done above the floor tiles as opposed to below them. Each cabling pathway will be sized to hold the cable and "spillovers" won't occur. This also assists with air flow issues. The likelihood of creating harm in the data center when you are under the floor working with cabling in a live environment increases in direct proportion to the mess under the floor. So in short, clean up and you won't steam up or error out! The benefits of a structured cabling system will provide payback in a short period of time through labor savings and certainly through electricity savings.

Carrie Higbie has been involved in the computing and networking industries for 20+ years. Carrie currently works with The Siemon Company as the Global Network Applications Market Manager to support the end-user and electronics communities. She participates with the IEEE, TIA and various consortiums for standards acceptance. She has extensive background in all aspects of networking and application development as a consultant, project manager, and Fortune 500 executive and has taught at a collegiate level. She speaks at industry events and has published several articles and whitepapers globally.

Carrie holds an MBA and MSBA. Carrie is an expert on TechTarget's, and Web sites and is on the board of advisors of She writes a weekly columns on a variety of topics. She is the President of the BladeSystems Alliance. Carrie has won the "Communication News" Editor's Choice Award for the last two years.

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