How to Build a 911-Style Data Center

>> TIA/EIA 568-A: "Commercial Building Telecommunications Cabling Standard." This standard specifies punch-down standards and other technical requirements.

>> TIA/EIA 568-B: "Commercial Building Telecommunications Cabling Standard." This is a follow-on to 568-A dealing with high-speed networks.

>> TIA/EIA 569-A: "Commercial Building Standard for Telecommunications Pathways and Spaces." Like it sounds, this standard deals with cable routing through the building.

>>TIA/EIA 606-A: "Administration Standard for Commercial Telecommunications Infrastructure." This includes documentation standards, which are crucial: How quickly you can troubleshoot a cable plant is directly related to the quality of its documentation.

Each time you punch down a cable, you're likely using parts of 568-B, the standard manufacturers use when labeling keystones with wire color, for example. And every time you think about how to route cabling, keep the 569-A standard in mind for your deployment. (This is functionally the same type of standard as ISO/IEC 11801 2nd edition, also a cable standard.)

For help in getting started on building out a quality wiring infrastructure or retrofitting your existing one, you have several options. You can buy the standards from TIA/EIA (see "Sites To See," page 82); Google to piece things together on your own, with or without using these standards; plow through a third-party book (for example, Barry J. Elliott's Designing a Structured Cabling System to ISO 11801 [Marcel Dekker, 2002] and Building Industry Consulting Service International's Telecommunications Cabling Installation [McGraw-Hill Professional, 2002]); or have your staff or cabling supplier attain a cabling certification. The BICSI's RCDD (Registered Communications Distribution Designer) is one such certification.

Your suppliers should be certified and up to speed on cabling standards, and you may want in-house expertise as well. For large enterprises, it's a good idea to have at least one staffer who's knowledgeable about wiring standards so you can keep tabs on suppliers' compliance and best practices. Also consider having an independent contractor audit your wiring project if it's large and you're not doing it in-house.

The basic tenet of wiring is that cable that looks good was likely installed right in the first place.This means following a few simple rules for wiring your data center. First, tie-wrap and bundle your cables, but use plastic tie wraps only for permanent bundles. Some enterprises avoid plastic altogether because it can damage the cable if you pull it too hard. Use Velcro for bundles that will be rewrapped or added to on a regular basis. And keep the lengths of your bundles of cable consistent and without much extra play. If your cable lengths are inconsistent, they can snarl, sprawl and snag.

When routing wiring on a rack, don't route over other devices (see "Rack-Routing Etiquette," page 81). Not only will it look bad, you'll regret such sloppy work when you need to perform maintenance on network devices. It's important for the front and back of a device to be in the clear so that when you pull that device for emergency replacement or service, you don't have to spend time unsnarling other devices' cables.

Use cable-management hoops or brackets to keep your cables or bundles on a consistent "track." Normally, this means you'll be routing on right angles, which looks good but depends on your routing devices. Hoops and brackets help you avoid snags and make cables easier to trace. You can tie-wrap your cable bundles to cable-management brackets, too, where necessary.

If you want to build a more complex wiring infrastructure, check out the books mentioned above and look at someone else's cabling. ("Sites To See" has a link for an example of one university's cabling standards.)

Labeling BasicsLabeling is always a problem with a cable plant. It's tough to troubleshoot when you have no idea which wire leads to what device. In an emergency outage, proper labeling can be the difference between a five-minute and one-hour response. Here are a few tips for labeling your wiring:

>> No paper please. Don't use paper labels for data cabling. They will rip and fall off.

>> Expensive label machine or cheap one? This doesn't really matter. A $500 machine does as well as a $30 machine--it's all about the labels. If you do use a machine that's not advertised as a cable-labeling system, first test the adhesive in a data-center environment. If you don't, you may have confetti flying around rather than tags labeling your patch panels and cables.

>> Server names or numbers? This is an individual decision, but one observation: Your cable plant should live through several generations of servers and routers. Numbers make sense, but this may not be popular with the left-brained set.

>> Labels for short-patch cables? Not if you can see both ends and the ends are traceable. If your labels are parts of bundles, you'll likely have to trace them anyway.Check TIA/EIA 606-A for more labeling guides.

We've seen plenty of data centers with beefy servers and redundant power supplies, but lacking multiple UPSs. Redundant power supplies on your device won't do you much good if your UPS isn't redundant. If you can set up an additional UPS in the data center, do it. This eliminates the risk of having one UPS as a single point of failure. To take advantage of an additional UPS, it's worth the effort to build out your power conduits with color-coded outlets that indicate which UPS each outlet represents. This will really help when it's time to hook redundant power supplies to diverse UPS sources. One UPS, for example, could have standard black outlets on its power conduits, while the other could have orange-colored power outlets on the conduits.

And if your power-supply units don't have tie wraps on their power supply cords, consider Velcro or plastic tie wraps. Many an outage is caused by someone knocking out an unsecured power cable.

Jonathan Feldman is director of information services for the city of Asheville, N.C., and a contributing editor to Network Computing. Previously he was director of professional services for Entre Solutions, an infrastructure consulting company based in Savannah, Ga. Write to him at [email protected].