Cable management and containment in high-density data centres

Cable management and containment in high-density data centres

Joost Grillaert, Product Manager at Nexans Cabling Solutions

The difficulty – or ease – of data centre cable management is closely related to data centre design. If cable management isn’t factored in during the design phase, things can soon become very complicated. Planning is essential. Although mapping cabling infrastructure and considering a wide range of eventualities and possible future needs may seem difficult and time-consuming at the outset, these efforts will always pay off once data centre installation commences.

Layout based on network architecture can support workflow going forward. With this approach, key elements can be optimised: cable lengths, installation time, capacity growth planning and supply chain management (for example by using pre-terminated cables, possibly pre-cut to required lengths and delivered exactly when required). The biggest cable management challenge is providing a scalable solution. 

This can be separated into cable management for trunks between racks and for patch cords inside the racks. What’s more, data centre infrastructure and installation methods may vary considerably, further complicating the issue. Some facilities may initially install only power and infrastructure components, and add cabinets according to demand. Others might prefer to use structured cabling and pathways for the cabling between and inside the racks.

Increasing density challenges

To meet the growing bandwidth and flexibility needs of today and tomorrow, density in cabinets is increasing. This requires careful planning and management as increased density can easily result in unmanageable cabling. We’re seeing cables with significantly higher fibre counts, which have a smaller diameter than previous generations of cables. There is a practical limit to how small a cable can be manufactured and still be handled properly. Large numbers of patch cords placed close to each other can be very tricky to manipulate accurately. Moves, Adds and Changes, cable tracking and fault-finding can become very challenging indeed. New Ethernet technologies will require higher density connectors, making installations even more challenging. On the plus side, the size reduction does contribute to helping manage cabling in the pathway. Cables take up less space, and can be more flexible, allowing for neater bundles. The weight reduction can also simplify pathway requirements.

As data centre networks densities increase, more connectors need to fit into a smaller space. This requires careful planning of pathways, and choosing connectors that accommodate intended use. If connections are to be used for patching and re-patching on an ongoing basis, it’s important that technicians can easily access the connectors. If you are not careful, the panels can become too dense. Keeping panels neat has become particularly important as densities increase. Integrating cable management into patch panels, for example by using angled panels and sliding trays, supports this. By respecting cables’ bend radii, making sure cables and bundles aren’t resting on each other, and carefully organising racks and trays, interference, transmission errors and permanent damage – and therefore downtime – can be avoided. 

Keep it cool

Fast-rising temperatures resulting from inefficient air movement can lead to significant damage. Cabling can have a significant impact on airflow. Rack inlet and exhaust fans need to be kept clear at all times. However, poor cabling practices can block direct airflow from equipment fans. Proper patch cord management, reduced diameter cords, and appropriate panels are ways of mitigating this problem.

Underfloor cabling can create air dams where cool air gets trapped and can’t move to the vents below the racks. Because the cables are below the floor and pretty much invisible, these issues can go unnoticed. This problem can be tackled by using cabling with a reduced diameter and observing proper pathway fill ratios. 

Cable containment solutions

In a data centre environment, pathway systems are complex, The choice of cable pathway is mainly related to the architecture, with fibre pathways typically used in the core of the access network and copper/fibre in the access network. A leaf-spine two-layer data centre network topology, use of leaf switches (connecting servers and storage connect) and spine switches (connecting leaf switches), requires a different approach. In this case, the access layer is formed by leaf switches meshing into the spine. 

Obstacles along the path need to be avoided. Cables can be run through pathways under the floor, but also placed above or inside cabinets. Overhead cabling solutions can easily take the shortest route between locations and air temperature is less of a concern. 

Cable ‘waterfalls’ from overhead supports can run into vertical wire managers without strain. Overhead cable management systems can safely run into racks and enclosures for patching or installations at any time. It’s important to observe that overhead structures need to align with cabinet rows in the horizontal plane, but also offer vertical supports are necessary to accommodate today’s high cable volumes. It’s also vital to ensure transitions to racks can maintain prescribed bend radii. The tray system should be easy to adjust and extend on-site, without adding sharp joint segments, and also comply with security and building standards.

A dedicated pathway should protect fibre optic cables and cords from accidental damage, offer sufficient capacity and be easy to install and reconfigure to meet future needs. A containment solution can provide a secure ducting for fibre optic cabling within a data centre, eliminating sharp edges that could cause harm. Moves, Adds and Changes of fibre optic patching becomes easier when cables are separated from a bunch of copper horizontal bundles. Future expansion and interconnection with channels of different sizes can be executed quickly.

Keeping track

Often, documenting patch cabling is overlooked, but inaccurate or incomplete documentation inevitably results in problems in provisioning new equipment, maintaining systems and troubleshooting. Today’s density and complexity call for automated, always up-to-date monitoring, mapping and management solutions. 

Of course, professional cable and connector management doesn’t exclusively rely on having the latest tools: quick wins include securely labelling cables and implementing consistent colour coding. 

Future-ready cabling

Changing requirements and (distributed) approaches to data centre architecture are offering considerable challenges to racking, containment and patching systems. In increasingly high-density environments, manipulating tightly packed, increasingly small cables and connectors can be tricky. So is ensuring cabling can run without being troubled by elevated temperatures, physical obstructions, crosstalk, and so on. 

When planning and specifying cabling routes and containment and management solutions, it is vital to first map the needs of each part of the network and consider how future changes can be accommodated quickly and easily. This should help ensure the backbone and patching installed today will continue to support operations for years, even decades to come.

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