Forum Server Room Racking

In an effort to keep the Forum Server Room layout reasonably neat and the machines located there maintainable, we want to insist on some general racking and cabling standards. The overall objectives are to arrange things so that:

  • any machine can easily be installed, worked on and maintained as necessary;
  • the cabling to any one machine does not interfere with the cabling or access to any other;
  • the risk of inadvertently disturbing one machine when working on any other is minimized;
  • we avoid problems in the future by routing cables in a standard way.

1. Racking

  1. Label all machines in racks on both their front and back panels. If a machine has a detachable front bezel, then that should also be labeled.
  2. Leave a 1U gap between all rack-mounted machines.
  3. Fill in any such 1U gap with a blanking plate (there is a supply of these in the server room), in order to encourage optimal air-flow.
  4. Generally, the top five or so rack slots are reserved for infrastructure purposes (network switches, fibre switches and console boxes). Disk arrays and heavy equipment (e.g. large servers like the Dell PowerEdge R900) should be installed in the lower slots of the racks; lighter 1U servers should be installed in the racks from the top down, starting from slot 37.

2. Cabling

  1. Most importantly: Use cables of an appropriate length.
  2. Run cables as tidily as possible, and secure where necessary using velcro strapping, rather than cable ties. (Velcro strapping which can be cut to the required length is available in the server room.) Any excess length in cables should be tidily coiled at the machine end, not the network switch/console server/power bar end.
  3. If you have to use cable ties, only use releasable ones, and do not overtighten: the cable jacket should not be deformed.
  4. Run cables from and to any machine in such a way that they don't interfere with access to the rear of any other machine in the same rack. In general, cables from a machine should first be routed sideways to the rack rails, strapped down there with velcro, and then run vertically. Cables should never be allowed to dangle straight down from the back of any machine.
  5. Don't use the cable arms that come with Dell servers: they over-complicate the cabling, restrict both access and air-flow, and can damage the cables. They are particularly unsuitable for routing fibre cables. Likewise, don't use the cable shelves that may have been supplied with Dell servers: they just create clutter.
  6. Bundles of cables running vertically at the sides of racks should be tidied as necessary using velcro strapping.


  1. Use IEC power cables of an appropriate length: we have such cables in lengths 0.5m, 1m, 2m, 3m, 4m and 5m.
  2. When connecting power cables to power bars, take care that the connections of neighbouring power cables are not disturbed: these connections are not as positive as you might expect.
  3. For machines with dual power supplies, connect each such supply to a different power bar. There are two power bars per rack for this purpose.
  4. Power cables should never need to be routed between racks.
  5. Note that the power bars are now under rfe control: please keep the configuration up-to-date as machines are installed and/or moved.

Network and consoles

  1. Use TP cables of an appropriate length: we have such cables in lengths 0.3m (orange), 0.5m (green), 1m (pink), 1.5m (blue), 2m (grey), 2.5m (yellow), 3m (purple), 4m (green) and 5m (red).
  2. Only use cables which are clearly labelled at both ends with an 'Inf' serial number.
  3. Route all cables that run between racks via the cable tray at the top of each bank of racks.
  4. For machines using ethernet bonding, connect the two interfaces involved to an even/odd pair of switches, e.g. sr00 and sr01; sr02 and sr03; sr04 and sr05; etc. This gives maximum redundancy, since the edge switches have themselves been connected so that each switch of such a pair uplinks back to a different core switch.

Fibre channel

  1. Use fibre cables of an appropriate length: we have such cables in lengths 0.5m (orange), 1m (purple), 2m (aqua), 3m (orange), 4m (purple) and 5m (aqua).
  2. Route all cables that run between racks via the cable tray at the top of each bank of racks.
  3. 'Spare' cable from any particular connection should be tidily coiled - either on top of the machine, or on top of the rack.
  4. Avoid any tight bends when routing the cable: the minimum bend radius for fibre is 3cm. (See:

3. General notes

  1. Spare IEC power cables are kept in bins above the cabinets in the server room; spare TP and fibre cables are kept within the same cabinets.
  2. If you find that there are insufficient spare cables of the appropriate length, please contact either the Inf Unit or the technicians so that more can be ordered.
  3. If you find that you need cables in lengths other than those which we have as standard, please contact the Inf Unit: cables of more-or-less any length can be ordered as necessary.
  4. If the power bars in the rack to which you're adding equipment have insufficient free outlets, please contact the Inf Unit: further power bars can be added to racks should this ever prove necessary.

-- IanDurkacz - 15 Oct 2008

Topic revision: r26 - 07 Sep 2019 - 08:39:14 - IanDurkacz
DICE.InfForumServerRoomRacking moved from DICE.InfForumServerRoomPlanning on 15 Oct 2008 - 12:07 by IanDurkacz - put it back
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