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
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 While many of the definitions are unchanged, some of the definitions may be out of date and some of the terms may no longer be in use in the Data Center industry.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.
Single Phase
Single Precision
A level of floating point accuracy that usually requires half the space for each value than does double precision, but provides considerably less precision. For most systems running the SPEC CPU tests from the OSG (e.g., CPU95), single precision implies a 32-bit value
Single-point Failure
Any component that has the capability of causing failure of a system or a portion of a system if it becomes inoperable
SKU
Stock keeping unit. Units within the same family of processors with differing attributes such as frequency, number of cores, wattage, and case temperature limits. Source: ASHRAE
SLA
Service level agreement
SLA
Service level agreements. Source: ASHRAE
SMF
Single-mode fiber
SNR
Signal-to-noise ratio
Solar Energy
Radiant energy emitted by the sun. Source: Oxford Languages
Solid
A substance or mixture which does not meet the definitions of liquid or a gas. Source: United Nations GHS
Sound Transmission Class (STC)
This is an acoustical rating for the reduction in sound of an assembly. It is typically used to denote the sound attenuation properties of building elements, such as walls, floors, and ceilings. The higher the STC, the better the sound-reducing performance of the element
Source Code
The human readable form of a computer program. This is typically the form in which the program is written, read, and modified by its human author(s)
SPEC95
A common (mis)name for the CPU95 benchmarks. Also, SPEC89 implies CPU89, SPEC92 should be CPU92, and SPEC2000 is CPU2000
SPECchem96
Official name of the Gamess application of SPEChpc96, an application representative of computations used by the chemical industry
SPEChpc96
The first benchmark suite released by SPEC/HPG, and it includes the two applications Seismic and Gamess
SPECjvm98
SPECjvm98 is the current Java Virtual Machine benchmark suite from SPEC
SPECmark
SPECmarks were the metrics for SPEC's original CPU89 benchmarks. Now, the term is often used to refer collectively to the CPU95 ratio speed metrics
SPECrate
A throughput metric based on the SPEC CPU benchmarks, such as SPEC CPU95. This metric measures a system's capacity for processing jobs of a specified type in a given amount of time. The metric is used the same for multi-processor systems and for uniprocessors. It is not necessarily a measure of how fast a processor might be, but rather a measure of how much work the one or more processors can accomplish. SPECrates are one style of metric from the SPEC CPU benchmarks, the other are SPECratios
SPECratio
A measure of how fast a given system might be. It is calculated by taking the elapsed time that was measured for a system to complete a specified job and dividing that into the reference time (the elapsed time that job took on a standardized reference machine). This measures how quickly, or more specifically, how many times faster than a particular reference machine, one system can perform a specified task. SPECratios are one style of metric from the SPEC CPU benchmarks, the other are SPECrates
SPECseis96
Official name of the Seismic application of SPEChpc96. It is an application representative of computations used by the seismic industry
SPECweb2005
SPECweb2005 is a standardized performance test for WWW servers, the successor to SPECweb99 and SPECweb99_SSL. The benchmark consists of different workloads (both SSL and non-SSL), such as banking and e-commerce, and writes dynamic content in scripting languages to more closely model real-world deployments. The web server also communicates with a lightweight backend to simulate an application/database server
SPECweb96
SPECweb96 is SPEC's first attempt at a benchmark for WWW servers. It measures a server's ability to handle HTTP/1.0 GET requests from a number of external client drivers
SPECweb99
SPECweb99 is one of the current web server benchmarks, which replaced the SPECweb96 product
Spillage
Volume of fluid present upon disconnection of fluid coupling pairs. Amount will vary depending on the type of shutoff integral to the connectors. Common fluid coupling embodiments may include poppet or flush-face valve types with flush-face generating the lesser amount of spillage. A flush-face connector may also be referred to as a no spill or dripless coupling, where the mating surface may only be minimally wetted on disconnection. Fluid coupling spillage is often a function of system pressure and flow rate on disconnection. Source: ASHRAE
Sponsor
For the OSG, the entity that has accepted the license agreement. In other words, the people who are responsible for ensuring that the results were obtained in accordance with any existing run and reporting rules. For the HPG, See benchmark sponsor who is a technical advisor for a particular benchmark
Spray Cooling
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
Spray/Jet Cooling
A classification type of data center cooling. Source: NVIDIA
Standard Performance Evaluation Corporation (SPEC)
An organization of computer industry vendors dedicated to developing standardized benchmarks and publishing reviewed results
Static RAM (SRAM)
Random access memory (RAM) that retains data bits in its memory as long as power is being supplied. SRAM provides faster access to data and is typically used for a computer's cache memory
Static UPS
See UPS, static
Steering Committee
Part of the SPEC bureaucracy. Each free-standing group within SPEC has a steering committee that acts as the key decision-making body with full membership votes typically being reserved for benchmark ratifications and elections
Stranded Assets
Assets exposed to devaluations or conversion to ‘liabilities’ because of unanticipated changes in their initially expected revenues due to innovations and/or evolutions of the business context, including changes in public regulations at the domestic and international levels. Source: IPCC
Substance
Chemical elements and their compounds in the natural state or obtained by any production process, including any additive necessary to preserve the stability of the product and any impurities derived from the process used, but excluding any solvent which may be separated without affecting the stability of the substance or changing its composition. Source: United Nations GHS
Substation
A set of equipment reducing the high voltage of electrical power transmission to that suitable for supply to consumers. Source: Oxford Languages
Supplemental label element
Any additional non-harmonized type of information supplied on the container of a hazardous product that is not required or specific under the GHS. In some cases, this information may be required by other competent authorities, or it may be additional information provided at the discretion of the manufacturer/distributor. Source: United Nations GHS
Supply Air
See air, supply
Sustainability (in context of Data Centers only for this model)
Data centers are subject to an expanding set of largely voluntary sustainability standards and requirements covering measurement and reporting, water and energy use, renewable energy procurement, equipment and system efficiency, greenhouse gas emissions management, adherence to a circular economy approach, and siting and design requirements. Investors and customers will increasingly use these standards to make investment and purchasing decisions. Legislators and regulators will use them as the basis of mandates governing the sustainability of operations and periodic sustainability reporting. Data Center operators will need to meet the requirements of many of these standards. Source: Uptime Institute
Sustainability Manager
A stakeholder in the decision to invest, divest, use, source liquid cooled data center environments. Source: United States Department of Energy CoE
Switch
A layer 2 interconnection device that conforms to the ISO/IEC 10038 [ANSI/IEEE 802.1D-1998]
Switchgear
Combination of electrical disconnects and/or circuit breakers meant to isolate equipment in or near an electrical substation
Symbol
A graphical element intended to succinctly convey information. Source: United Nations GHS
Symbol Rate (SR)
Within IEEE 802.3, the total number of symbols per second transferred to or from the medium dependent interface (MDI) on a single wire pair. For 100BASE-T4, the symbol rate is 25 MBd. For 100BASE-X, the symbol rate is 125 MBd. For 100BASE-T2, the symbol rate is 25 MBd. For 1000BASE-T, the symbol rate is 125 MBd
System Under Test (SUT)
The system being tested, as distinct from anything in the testbed being used to drive the test
System, Air Cooled
Conditioned air is supplied to the inlets of the rack/cabinet for convective cooling of the heat rejected by the components of the electronic equipment within the rack. It is understood that within the rack, the transport of heat from the actual source component (e.g., CPU) within the rack itself can be either liquid- or air-based, but the heat rejection media from the rack to the terminal cooling device outside of the rack is air
TC
Technical Committee. Source: TGG
TCE
Total cost to the environment. Source: Intel
TCLO
Total Cost of Liquid Operations. Source: TGG
TCO
Total cost of ownership. Source: ASHRAE
TCP/IP
A networking protocol developed for the creation of a robust internet being a connection across a variety of local networking mechanisms. The protocol used to connect to and through what is known today as the internet. The internet uses a layered architecture with several protocols. The TCP (Transmission Control Protocol) defines session-based communications, and the IP (Internet Protocol) addresses the lower-level issues of packet fragmentation and routing
TDP
Thermal design power. The maximum amount of heat generated by a component Source: ASHRAE
TDR
Time domain reflectometer
Technical Name
A name that is generally used in commerce, regulations, and codes to identify a substance or mixture, other than the IUPAC or CAS name, and that is recognized by the scientific community. Source: United Nations GHS
Telecom
Telecommunications
Temperature
The degree or intensity of heat present in a substance or object
Temperature, Dew-point
The temperature at which water vapor has reached the saturation point (100% relative humidity)
Temperature, Dry-bulb
Temperature of air indicated by an ordinary thermometer
Temperature, Wet-bulb
The temperature indicated by a psychrometer when the bulb of one thermometer is covered with a water-saturated wick over which air is caused to flow at approximately 4.5 m/s (900 ft/min) to reach an equilibrium temperature of water evaporating into air, where the heat of vaporization is supplied by the sensible heat of the air
Testbed
The entire test setup, including the SUT and any external systems used to drive, coordinate, or monitor the benchmark
TGG
The Green Grid, part of ITI and US Non-Profit professional organization. Source: TGG
Thermal Effectiveness
Measure of the amount of mixing between hot and cold airstreams before the supply air can enter the equipment and before the equipment discharge air can return to the air-handling unit
Thermal Efficiency
Energy output as a percentage of energy input of a machine or process
Thermal Storage Tank
Container used for the storage of thermal energy. Thermal storage systems are often used as a component of chilled-water systems
Thermosiphon
An arrangement of tubes for assisting circulation in a liquid through the use of capillary action
TIA
Telecommunications Industry Association
TIM
Thermal Interface Material: any material inserted between two parts to enhance the thermal coupling. Source: OCP
Tin Whiskers
See whiskers, tin
Tonnage
The unit of measure used in air conditioning to describe the heating or cooling capacity of a system. One ton of heat represents the amount of heat needed to melt one ton (2,000 lb) of ice in one hour. 12,000 Btu/h equals one ton of heat
TOR
Top of rack (network switch product). Source: ASHRAE
Total Heat (Enthalpy)
See heat, total
Turn-down Ratio
Ratio representing highest and lowest effective system capacity. Calculated by dividing the maximum system output by the minimum output at which steady output can be maintained. For example, a 3:1 turn-down ratio indicates that minimum operating capacity is one-third of the maximum
TWh
Terawatt-hour. Source: GEC
Twisted Pair
A cable element that consists of two insulated conductors twisted together in a regular fashion to form a balanced transmission line (from ISO/IEC 11801: 1995)
Twisted-pair Cable
A bundle of multiple twisted pairs within a single protective sheath (from ISO/IEC 11801: 1995)
Two Phase
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
UL
Underwriters Laboratories Research Organization. Source: UL
UN
United Nations. Source: United Nations GHS
Unshielded Twisted-pair Cable (UTP)
An electrically conducting cable, comprising one or more pairs, none of which is shielded. There may be an overall shield, in which case the cable is referred to as unshielded twisted-pair with overall shield (from ISO/IEC 11801: 1995)
Upflow
A type of air conditioning system that discharges air upward into an overhead duct system
UPS
Uninterruptible power supply
UPS
Uninterruptible power supply. Combination of convertors, switches, and energy storage devices (such as batteries) constituting a power system for maintaining continuity of load power in case of input power failure. Source: Energy Star
UPS Efficiency
Uninterruptible power supply efficiency. The output of an UPS in Watts divided by the input of power going into an UPS in Watts which results as a percentage without units. No UPS will be an input of 100%. Typically, an UPS will have 1-9% loss so the input would be 91 to 99%. Source: Energy Star
UPS, Rotary
A flywheel-driven UPS that is used for applications requiring ride-through of short-duration power system outages, voltage dips, etc. The flywheel-driven rotary UPS typically does not include batteries, and support times are usually on the order of a few seconds to a few minutes
UPS, Static
Typically uses batteries as an emergency power source to provide power to data communications facilities until emergency generators come on line
Uptime
* The time during which a computer is operational. Downtime is the time when it isn't operational
* Sometimes measured in terms of a percentile. For example, one standard for uptime that is sometimes discussed is a goal called five 9s, which is a computer that is operational 99.999 percent of the time
US
United States. Source: United Nations GHS
UTC
Coordinated Universal Time. Source: BIPM
Utility Computing
The vision of utility computing is to access information services in a fashion similar to those provided by telephone, cable TV, or electric utilities. It is a service provisioning model in which a service provider makes computing resources and infrastructure management available to the customer as needed and charges them for specific usage rather than a flat rate. Like other types of ondemand computing, such as grid computing, the utility model seeks to maximize the efficient use of resources and/or minimize associated costs
Valve
A device to stop or regulate the flow of fluid in a pipe or a duct by throttling
Vapor Barrier
A material or construction that adequately impedes the transmission of water vapor under specified conditions
Vapour
The gaseous form of a substance or mixture release from its liquid or solid-state. Source: United Nations GHS
Variable Frequency Drive (VFD)
A system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor
Variable Speed Drive (VSD)
A system for controlling the rotational speed of either an alternating current (AC) or direct current (DC) motor by varying the voltage to the electrical power supplied to the motor
VAV
Variable air volume
Vectorizable
The property of a computer program, or program segment, that allows for the simultaneous execution of operations on different data values, thus making it possible to allocate the work to a set of operators and accomplish the work in parallel. One example of work that is very vectorizable is taking an entire matrix of values and multiplying each by 2. It is possible for different operators to work on different cells of the matrix at the same time. One example of work that is not vectorizable is adding to each item in an array the value of the preceding item in the array as each calculation is dependent upon the results of the preceding calculation so there is no way to perform the operations at the same time. Vectorization is only one sub-class - probably one of the most restrictive sub-classes - of parallelizable programming
Velocity
* Vector Quantity: Denotes the simultaneous time rate of distance moved and the direction of a linear motion
* Face Velocity: Velocity obtained by dividing the volumetric flow rate by the component face area
Ventilation
The process of supplying or removing air by natural or mechanical means to or from any space. Such air may or may not have been conditioned
Vertical Overhead (VOH) Class
Refers to the delivery of air from overhead ductwork
Vertical Underfloor (VUF) Class
Refers to the delivery of air from an underfloor space, i.e., a raised-floor cavity
Virtual
Common alternative to logical, often used to refer to the artificial objects (such as addressable virtual memory larger than physical memory) created by a computer system to help the system control access to shared resources
Virtual Machine (VM)
A self-contained operating environment that behaves as if it is a separate computer. For example, Java applets run in a Java virtual machine that has no access to the host operating system. This design has two advantages:
* System Independence: An application will run the same in any VM regardless of the hardware and software underlying the system
* Security: Because the VM has no contact with the operating system, there is little possibility of a program damaging other files or applications. The second advantage, however, has a downside. Because programs running in a VM are separate from the operating system, they cannot take advantage of special operating system features