Power A good collocation facility will have a power system with backup units not only for the generator, but also the universal power supplies (UPS) and transfer switches or circuit breakers.

• UPSs run the servers while power switches from regular electricity to generators. Regardless of quality, UPSs fail regularly, so facilities must have multiple UPSs running sufficiently below capacity to manage the total server load if one fails. Transfer switches or circuit breakers switch power to the generators.

• Circuit breakers are more dependable than transfer switches, but it is important to have a backup for either system so that power can be transferred regardless of equipment failure.

• As the primary source of power during an outage, the generator must be large enough to handle 1.5 times the total building load. If there are multiple generators, the collocation facility must be able to transfer the load between generators, otherwise a failure could disable all generators.

Cooling An overlooked consideration for uptime and equipment maintenance is cooling. All servers generate heat yet are designed to operate at room temperature, between 72°F and 76°F. Computer room air conditioning (CRAC) units, chillers, and facility layout ensure that all servers receive adequate cooling. High-end collocation facilities regularly maintain cooling systems and monitor temperature, humidity, and power usage for optimum server performance.

• Chillers pipe cooled fluids to the CRAC units. There must be redundant pumps and chillers which automatically take over in case of failure so that the CRAC units continue to operate.

• CRAC units are large (20 to 30 tons), specialized air conditioners which constantly blow cold air. The minimum number of CRAC units to cool a facility is .030 tons per square foot. If there are four 30-ton units and the facility is 4,000 square feet, then there are .030 tons per square foot (120 tons ÷ 4000 square feet).

• The facility layout should have designated hot and cold rows. Server fans blow hot air from the back of the servers into hot rows; the CRAC units blow cold air down cold rows across the front of the servers. Solid floor facilities should have return vents on one side of the room to draw hot air from the servers, and cold air vents in the ceiling blowing down the top of the server racks. Raised floor designs should blow the cold air with enough pressure to force air to the top of the racks.

Internet Connection There are two major types of Internet connection.

• Tier 1 providers create national networks which are dependable and fast but tend to have high latency and poor out-of-network performance.

• Tier 2 companies buy access from multiple tier 1 networks, so they have speed and dependability combined with better latency and performance from a wider network. Some tier 2 providers offer performance routing to route traffic more efficiently between networks, boosting network performance by 50% and creating a self-healing network.

Service A quality collocation facility offers extra service, including any of the following:

• A dedicated, 24-hour customer service line, plus onsite engineers for emergencies.

• Changing backup tapes and storing them in a fire-proof safe.

• Crash carts with monitors, keyboards, and other tools available when a computer crashes.

• Structural designs to withstand earthquakes, storms, and floods.

Tour of the collocation facility, take notes and ask questions about their systems, backup systems, and maintenance, and find the facility with the service, access, and quality care to give your business reliable, dependable network.