S 1.69 Cabling in server rooms

Initiation responsibility: Head of IT

Implementation responsibility: Planner, Head of IT

The basic principles of structured cabling systems in EN 50173-1 "Information technology - Generic cabling systems - Part 1: General requirements" must also be followed, especially in server rooms and computer centres. An extension, EN 50173-5, has been developed and published as a draft standard especially for computer centres. This facilitates the implementation of the requirements in the standard for the user.

The requirements from the existing or planned network concept of the organisation form the basis for structured IT cabling in server rooms and computer centres. The structure specifies how the servers will be networked and how they are connected to the LAN, external networks, and providers. Systems supporting operations such as terminal servers, KVM switches, and SAN/NAS (Storage Area Network, Network Attached Storage) currently used or planned in the organisation must be taken into account with foresight. The basis for the structure of the access and concentration areas of the IT cabling, analogous to the building structures with floor distributions and building distributions, is therefore specified.

In larger installations, groups of cabinets in which servers are set up are often assigned to one "network cabinet". Permanent cables or special system cables for server rooms are installed between the network cabinets and the server cabinets assigned to them. The network cabinets are also connected to each other corresponding to the requirements of the organisation.

To optimally utilise the area available in the server room or computer centre, it is necessary to develop a room layout that meets the demands and requirements. In this room layout, the areas needed for the cabinets containing the systems operated by the organisation (storage systems and active and passive components as well as servers) must be specified with space reserved for future use. Safety aspects such as the layout of the escape routes, operational aspects such as the layout of the transportation paths, and climate control aspects must all be taken into account. The planning of the electrical power supply and the cable routes can then be performed based on this room layout.

It is recommended to use heavy-duty raised floors in server rooms and computer centres (see S 1.49 Technical and organisational requirements for the computer centre). If the false floor is used to supply air to the climate control systems in the cabinets, the tray systems must also be taken into account. Too many trays crossing each other between the fresh air supply in the false floor and the cabinets with high thermal loads located further away may result in "heat pockets". Although the air conditioning output is dimensioned sufficiently for the room, some cabinets, and the IT components stationed in these cabinets, do not receive enough cooled air. This results in a risk of failure of the servers or active components due to overheating.

In addition, it absolutely must be ensured that the screed or unfinished floor is sealed to prevent dust.

It is recommended to fasten all cables in place wherever possible. This requires proper installation of the cables in the tray systems in the raised floor or under the ceiling. If possible, servers should not be connected to server switches located in the middle of the room using patch cables without additional tray systems, even if this type of cable installation is commonly encountered in practice. Such "exposed cabling" is hazardous, particularly when cables are installed later.

Cabinet systems meeting the requirements of the organisation in which there are pre-mounted systems for routing cables and holding surplus cables permit organised and easy-to-maintain cable routes in the cabinet.

Even if only a few cabinets are networked, it is useful to install patch panels in the cabinet systems to connect the servers and to install a permanent connection from these patch panels to the network nodes in the server room. If a completely new design is to be performed, one patch panel per cabinet for category 6 or 7 copper cable (CAT 6 or CAT 7, suitable for 10 Gigabit connection) should be considered and, if necessary, equipping them with a fibre optic cable patch panel. The latter can be used, for example, to connect the servers to storage networks. Of course, the equipment of cabinets must be coordinated with the plans made by the organisation.

If there are no constructional issues speaking against it, routing the cables over cable trays installed under the ceiling of the server room is to be preferred to routing the cables through the raised floor. Routing the cables through the raised floor may adversely affect the required supply of cool air, especially when the space under the false floor is used for climate control. Furthermore, experience has shown that laying the cables in the raised floor also increases the risk of not removing unneeded cables. When the cables are routed through easily accessible trays on the ceiling, it is generally much easier to remove old cables.

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