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UPSes are a must in every data center. When selecting a UPS or adding equipment, you should make sure to pay careful attention to the capacity rating of the device. A UPS should not be so overburdened that it cannot provide enough time for the servers to shut down in an orderly fashion. An often overlooked problem with UPS systems is a lack of regular maintenance. The batteries in a UPS system need to be changed periodically. Failure to do so can cause the unit to become drained prematurely or even fail entirely in the event of a power loss.

Generators, in conjunction with UPS systems, are used to provide power when the public utility fails. The main considerations when looking at your generator equipment are waveform and frequency. Matching UPS systems with the proper generator can be difficult. Common wisdom says that increasing the generator-to-UPS ratio at least two to four times will eliminate most problems. In reality, this can lead to a waste of capacity, money and real estate.

In speaking with a representative of generator manufacturer Cummins Onan, we discovered that there are myriad issues: Generators and UPS systems may not work together, and bypass switches, load-transfer equipment, UPSes and other equipment must be carefully studied before implementation. You need to get together with representatives of both UPS and generator companies and draw on their experience.

Where's the Fire?

Fire-suppression systems can save your bacon from frying in the event of a conflagration in your data center or collocation facility. Most fire-suppression systems work by having smoke sensors detect smoke, then cutting the power to the data center. Administrators can stop clutching their hearts -- most data-center fires are electrical in nature, and most electrical fires go out when the power is cut. Compared with an inferno in the data center, an unceremonious crash is small potatoes.

Not only do fire-extinguishing systems in the data center have to meet local building code, they must also keep disruption to a minimum in the event of a fire. Halon is no longer legal to use because of the chemical's ozone-depletion properties, so ask about Halon replacements, such as HFC-27ea, and also ask about plain old water. Remember, a good data-center fire-protection system will cut power before deploying. Sprinkler systems can also be set to trigger in only the areas that are on fire, not in the whole data center. Contrary to popular opinion, water is easier to clean up and recover from than smoke. Smoke gets everywhere and, unlike water, is actively corrosive to your data-center equipment. Several effective techniques are available to clean up after water damage, and many companies, such as CBL Data Recovery Technologies, Data Clean Corp. and DriveSavers Data Recovery, specialize in this. Consult with your fire-prevention-system professional for the best method for your environment.

HVAC Matters

Another important consideration is HVAC systems. The temperature in a data center or collocation facility should be constant, with a nominal variance of about 2 degrees. Data-center HVAC systems should be separate from the main building's HVAC systems and should also be installed in pairs, with either HVAC unit able to take the entire load of the data center. This allows for regular maintenance and for backup in the event of HVAC failure. A third, smaller unit for occasional use during periods of extreme weather conditions is also good to have.

Another important environmental consideration is humidity: too much and you risk condensation and corrosion, too little and you risk experiencing damaging static electricity and spontaneous nosebleeds. You need to ascertain the Btu rating of every piece of equipment in your data center, then multiply that by the equipment you will be adding (after all, data centers only get bigger). Use this data to select the proper equipment to ensure not only your current cooling needs, but also your needs for the future. Appropriate placement of your AC equipment is also important in regard to airflow and proper cooling. Again, the advice of a professional is invaluable.

Liebert Corp., which provides systems that control temperature and humidity, condition power, and guard against outages, recommends temperatures between 71 and 73 degrees Fahrenheit and 50 percent relative humidity with a maximum swing of 3 percent per hour.

Physical Security

Sure, you know controlling access to your data center is important, but how long has it been since you looked at an access list? You might be surprised at the sheer number of people who can come and go from your data center without an escort or even a "by your leave." In many companies, people past a certain rank automatically gain access to all secured areas of the building. But does the vice president of human resources really need access to the data center? In our experience, people outside the IT organization who have access to the data center will, eventually, conduct tours. Soon hordes of unauthorized people will be getting a good look at your setup.

Even within the IT department, people who don't have a direct need to be in the data center (the average programmer, for example) should not have access. However, these are the people who will resent the restriction the most. A simple rule of thumb: If they don't need to touch the equipment, they should not have access. Expect push-back on this front because some IT employees will feel betrayed and angry at the apparent loss of trust. If you're diplomatic and consistent in enforcing the rules, however, they should come around. In the case of a collocation facility, ask about the qualifications of the provider's employees and the access policies it has in place.

Mapping and Management

Do you have miles of old, disconnected cable and a staff afraid to touch it? If your data center has never had a good cabling diagram drawn, the task of making one can seem daunting. However, if you want to be able to pinpoint problems, you need to know the location and purpose of every piece of cable. A clear diagram, careful planning and regular purges are key.

Do a diagram as best you can, then dive in and get that old cable out of there. Get upper management onboard and have a directive issued stating that when equipment is decommissioned, the removal plan includes not only the equipment but also the cabling associated with it. Appoint a cable czar and make it his or her responsibility to keep the cabling diagram current and available. Others must go through that person to add or remove cable. Soon, cabling will become part of the plan when installing or removing equipment, and the area under your raised floors will be neat and organized.

In the case of a collocation facility, cable management is an indicator of the professionalism of the provider. If the provider cannot show you detailed cable diagrams, think twice.