The lowest temperature (corrected to a standard pressure of 101.3 kPa) at which the application of an ignition source causes the vapours of a liquid to ignite under specific test conditions. Source: United Nations GHS
TGG Glossary
This is a glossary of older terms. While many of the definitions are unchanged, some of the definitions may be out of date and some of the terms may no longer be in use in the Data Center industry. This legacy glossary provides definitions for hundreds of information and communications technology (ICT) and data center terms and acronyms. Arranged alphabetically and searchable, the glossary explains common industry vocabulary.
Flash Point
Float Voltage
Optimum voltage level at which a battery string gives maximum life and full capacity
Floating Point
A class of arithmetic, typically used in scientific applications. Actually much like the values displayed by a calculator, the values can range from very large down to minute fractions but only the first several digits are available. Floating point is commonly used when the values being calculated can be very large - into the billions - or else involve fractions, e.g., the number of miles from earth to the next galaxy (billions and billions) or the precise temperature of a feverish baby (101.8). Floating point is the alternative to integer. For the purposes of classification for the CPU benchmarks, SPEC classifies an application to be a floating point application if that application typically spends 10% or more of its time in calculating floating point value
Flow coefficient
Dimensionless factor used to characterize the flow performance a fluid coupling set; a correlation of volumetric flowrate to pressure loss for a known liquid. Often reported as a Cv or Kv value, where a Cv value is representative of the volumetric flow rate expected to result in 1 psi (6.9 kPa) pressure loss. Expected flow coefficients of fluid couplings for water-cooled server applications may be between 0.1 and 8.0+, based on size of the fluid loop being served. Source: ASHRAE
Flow rate
Volumetric fluid flow rate supported for safe, reliable operation. When specifying a connector set, preferred installations promote maximum flow with minimal pressure loss. Typical ranges for water-cooled server applications may be 0.1 to 10 gpm (0.38 to 31.85 L/m). Source: ASHRAE
Fluorinert
A family of perfluorinated liquids from 3M offering unique properties ideally suited to the demanding requirements of electronics manufacturing, heat transfer, and other specialized applications
Fluorocarbon
A compound formed by replacing one or more of the hydrogen atoms in a hydrocarbon with fluorine atoms. Source: Oxford Languages
Flux
Amount of some quantity flowing across a given area (often a unit area perpendicular to the flow) per unit time. The quantity may be, for example, mass or volume of a fluid, electromagnetic energy, or number of particles
Footprint
In information technology, a footprint is the amount of space a particular unit of hardware or software occupies. Marketing brochures frequently state that a new hardware control unit or desktop display has a "smaller footprint," meaning that it occupies less space in the closet or on a desk. More recently, the term is used to describe microcomponents that take less space inside a computer
FPGA
Field programmable gate array. Source: ASHRAE
Full Disclosure Report
The complete documentation of a benchmark's results along with the relevant system and benchmark configuration information. There should be sufficient detail and coverage for someone else to be able to reproduce the tests. Each result available on this server has such a disclosure available
FWS
Facility water system. Source: ASHRAE
Gage-cock
A small cock fitted to a pressure or other measurement gage to allow for isolation of the gage for purposes of maintenance
Gas
A substance which (i) at 50 degrees Celsius has a vapour press of greater than 300 kPa (absolute); or (ii) is completely gaseous at 20 degrees Celsius at a standard pressure of 101.3 kPa. Source: United Nations GHS
Gateway
A hardware or software setup that translates between two dissimilar protocols, or commonly, any mechanism for providing access to another system
GEC
Global Electronics Council, a not-for-profit industry organization. Source: GEC
Gelled Electrolyte
See electrolyte, gelled
Generator
A dynamo or similar machine for converting mechanical energy into electricity. Source: Oxford Languages
Geometric Mean
A mean (average value) that is obtained through the use of multiplication and Nth roots rather than by addition and division. To calculate, take the Nth root (the power of 1/N) of the product of all N terms. The geometric mean has the interesting property that a certain percentage change in any one of the terms has the same effect as the same percentage change in any of the other terms and even successive changes in the same term will have the same effect as if the changes were instead spread over other terms. What this means in benchmarking terms is that a 10% improvement in one benchmark has the same effect on the overall mean as a 10% improvement on any of the other benchmarks and that another 10% improvement on that benchmark will have the same effect as the last 10% improvement. Thus no one benchmark in a suite becomes more important than any of the others in the suite
GHGs
Greenhouse gases. Source: GEC
GHS
Globally Harmonized Systems of Classification and Labelling of Chemicals. Source: United Nations GHS
Global Positioning System (GPS)
A system of satellites and receiving devices used to compute positions on earth
Global Warming Potential (GWP)
Global warming potential. Source: IPCC
Globally Harmonized Systems of Classification and Labelling of Chemicals
Globally Harmonized Systems of Classification and Labelling of Chemicals (GHS). Source: United Nations GHS
Governance
A comprehensive and inclusive concept of the full range of means for deciding, managing, implementing, and monitoring policies and measures. Whereas government is defined strictly in terms of the nation-state, the more inclusive concept of governance recognizes the contributions of various levels of government (global, international, regional, sub-national and local) and the contributing roles of the private sector, of nongovernmental actors, and of civil society to addressing the many types of issues facing the global community. Source: IPCC
gpm or g/m
Gallons per minute. Source: ASHRAE
GPU
Graphic processing unit. Source: ASHRAE
Graphic Processing Unit (GPU)
A component type of data center class server. Source: NVIDIA
Grid
The layout of an electrical distribution system. Source: United States Energy Information Administration
GWh
A unit of energy representing one billion 1,000,000,000-watt hours. Source: Eurostat
Hard Disk Drive (HDD)
the mechanism that controls positioning, reading, and writing of data and furnishes the largest amount of data storage for a PC. [KEY=110226;UNSPSC=43201803;V23.07 || IDEA || ISO 22745-11 COMPLIANCE Source: eOTD ECCMA Open Technical Dictionary is an ISO 22745 compliant dictionary managed by ECCMA
Heat Exchanger
Device to transfer heat between two physically separated fluids
* Counterflow heat exchanger: Heat exchanger in which fluids flow in opposite directions approximately parallel to each other
* Cross-flow heat exchanger: Heat exchanger in which fluids flow perpendicular to each other
* Heat pipe heat exchanger: See heat pipe
* Parallel-flow heat exchanger: Heat exchanger in which fluids flow approximately parallel to each other and in the same direction
* Plate heat exchanger or plate liquid cooler: Thin plates formed so that liquid to be cooled flows through passages between the plates and the cooling fluid flows through alternate passages
Heat Exchanger, Rotary
See exchanger, rotary heat
Heat Exchangers
A component of liquid cooling solutions. Source: TGG
Heat Load per Product Footprint
Calculated by using product measured power divided by the actual area covered by the base of the cabinet or equipment
Heat Load, Latent
Cooling load to remove latent heat, where latent heat is a change of enthalpy during a change of state
Heat Load, Sensible
The heat load that causes a change in temperature
Heat Pipe
Also defined as a type of heat exchanger. Tubular closed chamber containing a fluid in which heating one end of the pipe causes the liquid to vaporize and transfer to the other end where it condenses and dissipates its heat. The liquid that forms flows back toward the hot end by gravity or by means of a capillary wick
Heat Pipe
A classification type of data center cooling for high heat density liquid cooling of data center equipment. Uses indirect liquid cooling with a cold plate. Source: NVIDIA
Heat Sink
Component designed to transfer heat from an electronic device to a fluid. Processors, chipsets, and other high heat flux devices typically require heat sinks
Heat Transfer Effectiveness
The ratio of the actual amount of heat transferred to the maximum possible amount of heat that could be transferred with an infinite area, a parameter of evaluation for fluids used to cool data center equipment. Source: Che Resources
Heat, Total (Enthalpy)
A thermodynamic quantity equal to the sum of the internal energy of a system plus the product of the pressure-volume work done on the system: h = E + pv where h = enthalpy or total heat content, E = internal energy of the system, p = pressure, and v =volume. For the purposes here, h = sensible heat + latent heat. Sensible heat is heat that causes a change in temperature. Latent heat is the change of enthalpy during a change of state
Heating, ventilation, and air conditioning (HVAC)
Acronym used for heating, ventilation, and air conditioning systems. Source: Tech Target
HEPA
High-efficiency particulate air
HFCs
Numerous hydrofluorocarbons, an EPA targeted greenhouse chemical. Source: United States Environmental Protection Agency
High-efficiency Particulate Air (HEPA) Filters
These filters are designed to remove 99.97% or more of all airborne pollutants 0.3 microns or larger from the air that passes through the filter. There are different levels of cleanliness, and some HEPA filters are designed for even higher removal efficiencies and/or removal of smaller particles
High-performance Computing and Communications (HPCC)
Includes scientific workstations, supercomputer systems, high speed networks, special purpose and experimental systems, the new generation of large-scale parallel systems, and application and systems software with all components well integrated and linked over a high speed network
High-performance Group (HPG)
One of several groups within the SPEC organization. HPG has created the benchmark suite SPEChpc96, aiming at high-end machines including both shared-memory and distributed-memory architectures
High-performance Steering Committee (HPSC)
Executive group within HPG. Currently, HPG and HPSC are the same (i.e., all HPG members are part of HPSC)
Horizontal Displacement (HDP)
An air distribution system used predominantly in telecommunications central offices in Europe and Asia. Typically, this system introduces air horizontally from one end of a cold aisle
Horizontal Overhead (HOH)
An air distribution system that is used by some long-distance carriers in North America. This system introduces the supply air horizontally above the cold aisles and is generally utilized in raised-floor environments where the raised floor is used for cabling
Hot Aisle/Cold Aisle (from ASHRAE, industry)
* A common arrangement for the perforated tiles and the data communications equipment. Supply air is introduced into a region called the cold aisle
* On each side of the cold aisle, equipment racks are placed with their intake sides facing the cold aisle. A hot aisle is the region between the backs of two rows of racks
* The cooling air delivered is drawn into the intake side of the racks. This air heats up inside the racks and is exhausted from the back of the racks into the hot aisle
Hot Aisle/Cold Aisle (from ASHRAE)
A common means of providing cooling to data communications rooms in which IT equipment is arranged in rows and cold supply air is supplied to the cold aisle, pulled through the inlets of the IT equipment, and exhausted to a hot aisle to minimize recirculation of the hot exhaust air with the cold supply air
Hot Gas
Pressurized gas leaving the compressor (discharge) prior to entering the condensing surface
hp
Horsepower. Source: ASHRAE
HPC
High-performance computer; also called a supercomputer. Source: ASHRAE
HPC
High-performance computing
HSC
Hot-swap Controller. Source: OCP
Humidification
The process of adding moisture to air or gases
Humidifier, Warm Air Heating System
A device which, when installed in conjunction with a warm air heating system, injects or releases vapor for the purpose of increasing the relative humidity in a room or building. Excludes self-contained air humidifying units. [ FIIG=A23900;INC=15584 || DLIS || ISO 22745-11 Source: eOTD ECCMA Open Technical Dictionary is an ISO 22745 compliant dictionary managed by ECCMA
Humidity
Water vapor within a given space
* Absolute humidity: The mass of water vapor in a specific volume of a mixture of water vapor and dry air.
* Relative Humidity: Ratio of the partial pressure or density of water vapor to the saturation pressure or density, respectively, at the same dry-bulb temperature and barometric pressure of the ambient air. Ratio of the mole fraction of water vapor to the mole fraction of water vapor saturated at the same temperature and barometric pressure. At 100% relative humidity, the dry-bulb, wet-bulb, and dew-point temperatures are equal
Humidity Ratio
The ratio of the mass of water to the total mass of a moist air sample. It is usually expressed as grams of water per kilogram of dry air (gw/kgda) or as pounds of water per pound of dry air (lbw/lbda)
Humidity, Relative
See relative humidity
HVAC System Efficiency
See efficiency, HVAC system
Hydrofluorocarbon (HFC)
A halocarbon that contains only fluorine, carbon, and hydrogen
Hydronic
A term pertaining to water used for heating or cooling systems
Hygroscopic Dust Failure (HDF)
Sulfate and nitrate salts to which water adheres and promotes corrosion
Hyperscale Data Center
Massive business-critical facilities designed to efficiently support robust, scalable applications and are often associated with big data-producing companies such as Google, Amazon, Facebook, IBM, and Microsoft. Source: Vertivxv
HyperText Transmission Protocol (HTTP)
The protocol over TCP/IP by which the worldwide web communicates. The specifications for HTTP are available from the World Wide Web Consortium, which develops such standards
IC
Integrated Circuit. Source: GEC
IEC
The International Electrotechnical Commission. Source: EU
IEEE
Formerly, the Institute of Electrical and Electronics Engineers, Inc.
Immersion
A classification type of data center liquid cooling. Source: NVIDIA
Immersion Cooling
A type of liquid cooling used to cool servers, motherboards, CPUs, and GPUs. The entire server is immersed in a liquid. The liquid cools the system directly, and the warmer liquid rises. The hot liquid is then removed from the container and refrigerated separately. The liquid used for immersion cooling is nonconductive and non- corrosive, so that it may be used with electronic components. Source: Supermicro
In Rack Heat Exchanger (IRHx)
A specialized IT Cabinet read door with a built-in heat exchanger that uses a radiator where the hottest servers are operating. Source: Supermicro
Indirect water-cooled
Power that is transferred indirectly to water through an air-to-water heat exchanger located within or on the rack (could be a rear door heat exchanger). Source: ASHRAE
Infiltration
Flow of outdoor air into a building through cracks and other unintentional openings and through the normal use of exterior doors for entrance and egress. Also known as air leakage into a building
Information and communication technology (ICT)
An umbrella term that includes any information and communication device or application, encompassing: computer systems, network hardware and software, cell phones, etc. Source: IPCC
Information Technology (IT)
THIS SEGMENT INCLUDES COMMUNICATIONS AND COMPUTER EQUIPMENT AS WELL AS PERIPHERAL INPUT, OUTPUT AND STORAGE DEVICES. THIS SEGMENT ALSO INCLUDES NETWORKING EQUIPMENT AND GENERAL COMPUTER COMPONENTS AND SUPPLIES SUCH AS PRINTERS, ELECTRONIC STORAGE MEDIA AND CONNECTION CABLES. [ UNSPSC=43000000 || ECCMA || ISO 22745-11 COMPLIANCE Source: eOTD ECCMA Open Technical Dictionary is an ISO 22745 compliant dictionary managed by ECCMA
Information Technology Equipment (ITE)
Computers, data storage, server, and network / communication equipment. Source: eOTD ECCMA Open Technical Dictionary is an ISO 22745 compliant dictionary managed by ECCMA
Initial boiling point
The temperature of a liquid at which its vapour pressure is equal to the standard pressure (101.3 kPa) i.e., the first gas bubble appears. Source: United Nations GHS
Integer
A class of arithmetic, commonly used in computers. Integer arithmetic deals only in whole numbers, e.g., 1, 2, 99, 4563. Any calculation that does not result in a nice whole number is truncated back to a nice whole number and the fractional part is thrown away, e.g., 9/4 = 2 and not 2.25 or two and a quarter. Typically, computers can perform integer arithmetic more quickly than they can any other form of arithmetic, so most programs do as much work as they can in integer. However, most computers have significant limits on the values they can manage in integer format. Besides the lack of fractions, many computers cannot handle integer values beyond the millions. Thus, integers can be used to count time or to keep track of all the pennies in your bank account. However, most scientific applications deal with large values or need to be more precise than just throwing away the fractions. These kind of applications then make use of floating point arithmetic. For the SPEC CPU benchmarks, applications are classified as "integer" if they spend less than 1% of their time performing floating point calculations (which covers most non-scientific applications, e.g., compilers, utilities, simulators, etc.
Integrated switch
A component type of data center class server. Source: Intel
Intergovernmental Panel on Climate Change (IPCC)
Intergovernmental Panel on Climate Change (IPCC) Source: IPCC
International Electrotechnical Commission (IEC)
A global organization that prepares and publishes international standards for all electrical, electronic, and related technologies
Iron Whiskers
See whiskers, iron
ISO
International Organization for Standardization
ISO
International Organization for Standardization. Source: United Nations GHS
IT
Information technology
ITE
Information technology equipment
ITRS
International technology roadmap for semiconductors
ITU-T
The International Telecommunication Union and telecommunication standardization sector. Source: EU
IUPAC
International Union of Pure and Applied Chemistry. Source: United Nations GHS
Jet Impingement
A classification type of data center cooling for high heat density liquid cooling of data center equipment. Uses direct liquid cooling through immersion or spray. Source: NVIDIA
Kelvin (K)
The SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 x 10-23 when expressed in the unit J K-1, which is equal to kg m2 s-2 K-1, where the kilogram, meter and second are defined in terms of h, c and ΔνCs. Source: BIPM
Keyboard-video-mouse (KVM) Switch
A piece of hardware that connects two or more computers to a single keyboard, monitor, and mouse
Kilogram (kg)
The SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in the unit J s, which is equal to kg m2 s-1, where the meter and the second are defined in terms of c and ΔνCs. Source: BIPM
Kilowatt
A measure of 1,000 watts of electrical power. Source: Oxford Languages
Kilowatt-hour
A measure of electrical energy equivalent to a power consumption of 1,000 watts for 1 hour. Source: Oxford Languages
kPa
Kilopascal a unit of pressure. Source: ASHRAE