Glossary

amps

A steady state current that is created by applying one volt across one ohm of resistance. To calculate amps, divide watts by volts. Watts · Volts = Amps.

basic thermal unit or British thermal unit (BTU)

This could be called either, depending on whom you ask. It is a measure of the amount of thermal energy required to raise by one degree 16 oz of water. To calculate BTUs per hour, multiply watts by 3.42. Watts x 3.42 = BTUs per hour .

Bolognese sauce

A tomato/meat sauce for use on pasta. Al's Mom's Recipe for "Quick Sauce" a.k.a. Bolognese sauce, printed with permission of Fran Mello.

Ingredients:

1 lb ground meat (usually beef but could be chicken)

2 Tbs olive oil

2-3 cloves of fresh crushed garlic

2-3 crushed tomatoes or about a cup and half of tomato puree.

Oregano, salt, and pepper to taste.

Braise the meat in the olive oil and garlic. Add the crushed tomatoes or tomato puree. Cook this mixture over medium heat for as long as it takes your pasta to cook, once the water is at the boil. Add the oregano, salt, and pepper to taste.

electrostatic discharge (ESD)

The static shock you might give by walking across carpet with wool socks and touching a metal door knob. While a fairly minor annoyance in most areas of life, ESD can wreak havoc with electronic components , causing equipment failure.

heating, ventilation , and air-conditioning (HVAC)

This generally refers to the air conditioning system in the data center.

plenum

From the Latin plenus. A area of a room filled with air such as the space between the subfloor and the raised floor, used to move cooling air to racks on the floor.

point of distribution (POD)

A rack containing network switches, terminal servers, and network cable patch ports.

power distribution unit (PDU)

An electrical distribution box fed by a 100 Amp three-phase Hubble connector. This box contains power outlets and circuit breakers.

psychrometry

The study of moist air and the changes in its conditions.

quality of service (QoS)

The delivery of a specific amount of network bandwidth. Defined for Ethernet in the IEEE 802.3q specification.

rack location units (RLU)

A set of specifications (power, cooling, physical space, network connectivity, rack weight, and logical capacity) used to define a rack of computer equipment and serve as a measure for determining data center requirements.

relative humidity (RH)

The ratio of how much moisture is in a volume of air, relative to how much moisture the same volume of air can hold. If you have a 50 percent relative humidity, the air could hold twice as much moisture as it is currently holding.

reverse engineering

The ability to take a completed system and work backwards to figure out how it was constructed .

U

A unit of measure for the sizing of network equipment. 1U is equal to 1.75 inches (44.45 mm) in height. A typical 7- foot rack contains about 6.5 feet of usable rack space, or 45 U tall (1.75 in. x 45 = 78.75 in.). When you are calculating how many devices you can fit in a rack, you need to know the number of Us of each device.

uninterruptible power supply (UPS)

A very large battery capable of sustaining power load for a given amount of time. If power is fed to it continuously, it can also serve as a power filter.

virtual private network (VPN)

To send data in a secure fashion over a unsecured network through encryption.

volts

The difference in electrical potential between two points on a conductive wire carrying a one ampere constant current. To calculate volts, divide watts by amps.

(Watts · Amps = Volts)

wide area network (WAN)

Special purpose networks to provide connectivity to multiple locations in different areas.

watts

Equal to 1/746 horsepower. To calculate watts, multiply volts times amps.

(Volts x Amps = Watts)