Cable type and placement affect network efficiency

Dec. 1, 2011
The rise of preterminated solutions has helped gain installation efficiency, and the overhead-or-underfloor placement issue is getting scrutinized.

From the December, 2011 Issue of Cabling Installation & Maintenance Magazine

The rise of preterminated solutions has helped gain installation efficiency, and the overhead-or-underfloor placement issue is getting scrutinized.

by Patrick McLaughlin

The theme of efficiency remains a constant goal and challenge in all spheres for data center administrators. The data center network’s physical layer is no exception; in fact, efficiencies in cabling-system designs and installations can promote efficiencies in other aspects of data center management. On the flipside, inefficient cabling practices can negatively impact other areas of network administration in the data center and
Whether in a data center or across an enterprise, operating a “green,” energy-efficient network involves much more than just purchasing and opening a box. The types of cabling selected to support the network, and the manner in which that cabling is managed, make a difference.elsewhere.

During a seminar entitled “Cabling, Cooling and Managing the Data Center” delivered via the Web in July 2011, Aaron Stout, a data center integrator with CommScope (www.commscope.com), delivered a presentation on achieving rapid deployment within data center environments. His presentation covered a range of topics including premanufactured systems such as containerized data centers, and also detailed some of the cabling choices that can be made within any type of facility.

“Even if you don’t use premanufactured whitespace solutions,” Stout explained, “using a modular approach will allow you to create a predictable expansion model.” This approach allows the facility owner to make purchases as they are needed rather than building a larger-than-needed capacity to begin with. “It also allows you to create technology-optimized architectures and infrastructures,” Stout noted. “A modular approach allows you to customize areas of your data center that you can repeat as needed to scale capacity up and down.” Additionally, a modular approach such as this, in which a facility is organized into zones, pods or units, enables the owner to refresh a specific area when its technology has become outdated and needs to be updated. The modular style also makes operational support of these areas more predictable and easier to manage than it is in facilities that lack this organizational structure.

Speaking of cabling in particular, Stout brought a point home by reminding us, “Money that is spent on a data center is not going to help you until you have applications up and running. Premanufactured systems allow you to get your applications running in a much faster manner.” Preterminated cabling systems have grown in popularity in data center networks and for fiber-optic cabling, preterminated systems represent the majority of new installations in North America.

Preterminated copper systems are also available and targeted to data centers. In addition to significantly decreasing installation times like their fiber-optic counterparts do, preterminated copper systems help reduce the waste generated at an installation site. Waste reduction is not only environmentally conscious; it also is a practical asset in a data center where the installation of a preterminated copper system eliminates the possibility of small shards of the metal doing damage to IT systems.

Cable management’s impact

In terms of data center turnup, efficiencies are being realized in ways as varied as the construction of the facility itself, to the use of layer-one infrastructure within the data center’s networks. But perhaps more than any other area, the consumption of energy is where the word “efficiency” is emphasized for data center environments. Two recent white papers produced by vendors serving enterprise and data center networks discuss how different aspects of network and cable management can have direct impact, positive or negative, on the facility’s energy-efficiency level.

One paper, authored by APC by Schneider Electric’s Victor Avelar, is entitled “How Overhead Cabing Saves Energy in Data Centers.” Available at APC.com, the paper states in its executive summary that placing data center power and data cables in overhead cable trays instead of under raised floors can result in an energy savings of 24 percent. “Raised floors filled with cabling and other obstructions make it difficult to supply cold air to racks,” it says. “The raised floor cable cutouts necessary to provide cable access to racks and PDUs [power distribution units] result in a cold air leakage of 35 percent. The cable blockage and air leakage problems lead to the need for increased fan power, oversized cooling units, increased pump power, and lower cooling set points.”

We have reported in the past on the perils of mismanaged cabling in data centers, and based on the fact that white papers like this one are still being issued, it is evident that the issue remains a problem in some facilities. Nearly five years ago (see “Performance, workmanship play key roles in data centers,” February 2007) we quoted Siemon’s global director for data center solutions and services, Carrie Higbie, as follows: “In many data centers, the cabling is not a planned system. They first installed some cables because they need a server and needed connectivity to that server. Plenty of data centers have cables clothes-lined across the room.” It is likely that in the years since then, many more data center facilities have realized the necessity of adding structure to their network cabling systems. Even so, the nuances of physically laying out and managing those cabling systems continue to present challenges.

The APC by Schneider white paper quantifies the amount of energy that can be saved by routing cables overhead instead of under floors, and presents the data in a number of tables. But within the paper, author Victor Avelar acknowledges, “Even overhead cabling can develop the problem of a cable ‘spaghetti’—a huge bunch of cables, tangled with each other. When this occurs, new cable cannot be laid because it is impossible to pull out ‘dead’ cable from the pile of existing cables. Cable trays begin to sag under the weight of cables, and this increases the risk of a fault in equipment operation.”

He provides further detail on the problem of an overhead cable mess, then advises, “The solution to this dilemma is to organize cable trays which are mounted at different levels. Multi-level cable tray organization allows data center personnel to sort and plan cable location, integration and removal on an ongoing basis. If a ‘dead’ cable needs to be removed, it will not be tangled or buried. It will be easy to extract the cable from a single small bundle.”

The hole picture

Another white paper, this one authored by Chatsworth Products Inc.’s (www.chatsworth.com) thermal design manager Travis North, addresses the issue of cabinet perforation and its impact on airflow. Professionals in the cabling industry have been lectured for years on the importance of managing cables that reside near dense populations of network equipment—particularly in data centers—so the cables do not impede the airflow that serves to cool down that equipment. One path for the air that flows through a cabinet or enclosure full of network equipment is the perforated door of that cabinet.

In the paper, North explains, “When choosing a cabinet door for your data center it is essential to ask yourself what level of perforation will be needed. Opinions on this subject are extensive, and some experts will tell you that for high-density heat loads of 30 kilowatts and above, you need 80-percent perforation, while others will say only 64-percent perforation is needed. Data center technology develops at a rapid pace and every day new discoveries are uncovered, which is why there is more to this question than just a single number.”

The paper is based on research conducted by Chatsworth Products and seeks to help users determine the level of cabinet perforation that best suits their specific applications. Among the conclusions reached in the paper are that, “for a large cross-sectional area, using a perforation of 64 percent does not impact airflow and there is no loss in performance even at extreme density loads of 30 kW and above.” The paper is available for download at Chatsworth’s Web site.

In the enterprise

While data centers typically garner the most attention for their efforts to maximize energy efficiency, enterprise-network environments of many types also strive for such accomplishments. A recent survey of European business enterprises conducted by CommScope brought that fact to light. The survey “revealed that the majority of businesses, 55 percent, expect investment in network infrastructure to grow by 10 to 25 percent in 2012, despite the continued struggles of the global economy,” CommScope said. “This increased investment will be fueled primarily by the implementation of environmentally friendly IT solutions, with network reliability and network intelligence as other key factors.”

In a release announcing the survey results, CommScope added, “Demand for ‘green’ IT solutions in the enterprise is already strong, with 84 percent of organizations having taken steps to improve the energy efficiency of their networks during 2011. Investment is set to continue next year with 46 percent of enterprises believing it is the most effective approach to achieving cost efficiencies in the network, which was cited by nearly half of all enterprises as the most significant goal of 2012.”

Koen ter Linde, CommScope’s vice president of enterprise sales for Europe, commented, “Our research shows that network managers are focused on achieving more efficient, intelligent and robust networks. Crucially, it reveals a widespread strategy to achieve cost efficiencies by investing in solutions that are proven to optimize performance and increase reliability, as opposed to simply reducing expenditure or opting for lesser-quality alternatives. The importance of these issues is only going to grow in time and we fully expect organizations, at the very least, to ensure they have a clear upgrade path to energy-efficient and intelligent infrastructure, allowing them to deploy full-scale upgrades when the time is right.”

Efficiently operating a network, whether across an enterprise, within a data center or both, requires significant consideration and planning for the future. That planning should always include the physical-layer infrastructure and the extent to which that infrastructure can be an asset or a liability with respect to efficiency.

Patrick McLaughlin is chief editor of Cabling Installation & Maintenance.

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