Data Center Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing data centers and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

  • #

    64-bit processor

    A 64-bit processor is a microprocessor with a word size of 64 bits, a requirement for memory and data intensive applications such as computer-aided design (CAD) applications, database management systems, technical and scientific applications, and high-performance servers.

  • A

    abend (abnormal end)

    An abend (a combining of two words, abnormal end, when operator messages were as short as possible) is an abnormal, rather than planned, end or termination of a computer program because of some problem with how it is running.

  • access layer

    The access layer is where host computers and end users connect to the network.

  • ACF2 or CA-ACF2 (Access Control Facility)

    ACF2 (more formally, CA-ACF2; the ACF stands for Access Control Facility) is a set of programs from Computer Associates that enable security on mainframes.

  • alien crosstalk (AXT)

    Alien crosstalk (AXT) is electromagnetic noise that can occur in a cable that runs alongside one or more other signal-carrying cables.

  • ambient temperature

    Ambient temperature is the air temperature of any object or environment where equipment is stored.

  • Andrew

    Andrew was a joint project between Carnegie-Mellon University and IBM to set up a distributed computing environment on the CMU campus.

  • ANSI (American National Standards Institute)

    ANSI, American National Standards Institute, organization for fostering, development of technology standards, industry groups, International Organization for Standardization, ISO, International Electrotechnical Commission, IEC, computer standards, American Standard Code, Information Interchange, ASCI, Small Computer System Interface, SCSI, what is, definition, term, glossary

  • ARM server

    An advanced RISC machine (ARM) server is an enterprise-class computer server that employs a large array of ARM processors rather than a complement of x86-class processors.

  • ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers)

    ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) is an organization devoted to the advancement of indoor-environment-control technology in the heating, ventilation and air conditioning (HVAC) industry

  • assembler

    An assembler is a program that takes basic computer instructions and converts them into a pattern of bits that the computer's processor can use to perform its basic operations.

  • automatic transfer switch (ATS)

    An automatic transfer switch (ATS) is a device that automatically transfers a power supply from its primary source to a backup source when it senses a failure or outage in the primary source.

  • B

    back-end

    Front-end and back-end are terms used to characterize program interfaces and services relative to the initial user of these interfaces and services.

  • baffle (data center hot aisle containment)

    Baffle paneling covers unwanted space between racks, under the raised floor and above dropped ceilings in the data center, reducing energy consumption and power use.

  • BAL (Basic Assembler Language or branch-and-link)

    BAL (Basic Assembler Language) is a version of IBM's assembler language (sometimes called assembly language) for its System/360 and System/370 mainframe operating systems.

  • bash (Bourne Again Shell)

    Bash (Bourne Again Shell ) is the free version of the Bourne shell distributed with Linux and GNU operating systems.

  • Basic Assembler Language (BAL)

    BAL (Basic Assembler Language) is a version of IBM's assembler language (sometimes called assembly language) for its System/360 and System/370 mainframe operating system.

  • batch

    In a computer, a batch job is a program that is assigned to the computer to run without further user interaction.

  • Beowulf

    Beowulf is an approach to building a supercomputer as a cluster of commodity off-the-shelf personal computers, interconnected with a local area network technology like Ethernet, and running programs written for parallel processing.

  • blade server

    A blade server, sometimes referred to as a high-density server, is a compact device containing a computer used to manage and distribute data in a collection of computers and systems, called a network.

  • Bloom Energy Server (Bloom box)

    A Bloom Box, officially known as an Bloom Energy Server, is a modular stack of solid oxide fuel cells that can produce electricity.

  • bogomips

    Bogomips is a measurement provided in the Linux operating system that indicates in a relative way how fast the computer processor runs.

  • boot loader (boot manager)

    A boot loader, also called a boot manager, is a small program that places the operating system (OS) of a computer into memory...

  • Bourne shell

    The Bourne shell is the original UNIX shell (command execution program, often called a command interpreter) that was developed at AT&T. Named for its developer, Stephen Bourne, the Bourne shell is also known by its program name, "sh". The shell prompt (character displayed to indicate readiness for input) used is the "$" symbol. The Bourne shell family includes the Bourne, Korn shell, bash, and zsh shells.

  • brick server

    A brick server is a compact computer server module without a chassis that can come in various processor, RAM, I/O, and storage configurations and is designed to fit into rack locations similar to those for blade servers.

  • brownfield (brownfield deployment, brownfield site)

    A brownfield deployment, in information technology, is the installation and configuration of new hardware or software that must coexist with legacy IT systems.

  • BSD (Berkeley Software Distribution)

    BSD (originally: Berkeley Software Distribution) refers to the particular version of the UNIX operating system that was developed at and distributed from the University of California at Berkeley.

  • building management system

    Building management system (BMS) is a computer system that tracks power used by IT equipment and air conditioning systems in the data center.

  • C

    CADE (Corporate Average Data center Efficiency)

    CADE (Corporate Average Data center Efficiency) is a metric used to rate the overall energy efficiency of an organization's data centers. CADE was introduced in a joint Uptime Institute and McKinsey report that proposed the metric as a single key performance indicator that could be used to compare the energy consumption of one data center against another. CADE combines measurements of the energy efficiency and utilization of IT equipment and facilities into a single percentage. (Continued...)

  • Calibrated Vectored Cooling (CVC)

    Calibrated Vectored Cooling (CVC) is an air-cooling technology developed by IBM for server systems with high component density.

  • capacity on demand (COD)

    Capacity on demand (COD) is a purchasing option that allows companies to receive equipment with more computer processing, storage, or other capacity than the company needs at the time of purchase, and have that extra capacity remain unused and unpaid for until the company actually requires it.

  • carbon usage effectiveness (CUE)

    Carbon usage effectiveness (CUE) is a metric developed by The Green Grid to help organizations measure the amount of carbon used -- or carbon footprint -- in the daily operations of their data centers.

  • Categories of twisted pair cabling systems

    ANSI/EIA (American National Standards Institute/Electronic Industries Association) Standard 568 is one of several standards that specify "categories" (the singular is commonly referred to as "CAT") of twisted pair cabling systems, such as wires, junctions, and connectors.

  • CEEDA (Certified Energy-Efficient Datacenter Award)

    CEEDA is a data center certification for the efficient use of energy.

  • channel

    In telecommunications in general, a channel is a separate path through which signals can flow. Depending on the context, this term has various meanings.

  • channel extender

    A channel extender is a device used with IBM's S/390 line of computers to increase the maximum communication distances between the S/390 channel-connected mainframe computers, or between an S/390 and peripheral devices such as workstations, printers, and storage devices.

  • chmod (change mode)

    In a UNIX-based operating system, chmod (change mode) is a command used by a file owner or administrator to change the definition of access permissions to a file or set of files.

  • CICS (Customer Information Control System)

    CICS (Customer Information Control System) is an online transaction processing (OLTP) program from IBM that, together with the COBOL programming language, has formed over the past several decades the most common set of tools for building customer transaction applications in the world of large enterprise mainframe computing.

  • Cisco Catalyst Blade Switch 3020

    The Cisco Catalyst Blade Switch 3020 is a switch designed for the Hewlett-Packard (HP) BladeSystem c-Class of blade servers... (Continued)

  • CMDB (configuration management database)

    A configuration management database (CMDB) is a file -- usually, in the form of a standardized database -- that contains all relevant information about the hardware and software components used in an organization's IT (information technology) services and the relationships between those components.

  • colocation marketplace

    A colocation marketplace is an online platform that connects colocation users with managed service providers, IT vendors and potential business partners.

  • compaction

    In a data center, compaction is the reduction or consolidation of hardware to make better use of physical floor space.

  • computer room air conditioning unit (CRAC)

    A computer room air conditioning (CRAC) unit is a device that monitors and maintains the temperature, air distribution and humidity in a network room or data center. CRAC units are replacing air-conditioning units that were used in the past to cool data centers. According to Industrial Market Trends, mainframes and racks of servers can get as hot as a seven-foot tower of powered toaster ovens, so climate control is an important part of the data center's infrastructure.

  • computer room air handler (CRAH)

    A computer room air handler (CRAH) is a device used frequently in data centers to deal with the heat produced by equipment.

  • computer-intensive

    Computer-intensive is a term that applies to any computing application that requires the resources of a lot of computers, such as grid computing.

  • computerized maintenance management system (CMMS)

    A computerized maintenance management system (CMMS) is software that helps operations and maintenance staff identify and track the status of maintenance tasks and availability of replacement parts.

  • converged data center

    A converged data center pre-integrates server, storage and networking hardware with management, hypervisor and operating system platforms, as well as applications and services.

  • COTS (commercial off-the-shelf)

    COTS (commercial off-the-shelf) describes ready-made products that can easily be obtained.

  • COTS, MOTS, GOTS, and NOTS

    COTS, MOTS, GOTS, and NOTS are abbreviations that describe pre-packaged software or hardware purchase alternatives.

  • cow power (biogas)

    Cow power is a term for the conversion of manure to usable energy. The energy produced can supplement the electric power offered by a utility or power a facility, such as a factory or a data center.

  • CRON script

    A CRON script is a list of one or more commands to a computer operating system or application server that are to be executed at a specified time.

  • crontab

    crontab is a UNIX command that creates a table or list of commands, each of which is to be executed by the operating system at a specified time.

  • crossbar latch

    A crossbar latch, also called a molecular crossbar latch, is a nanoscale device with properties similar to those of a conventional silicon transistor, but physically much smaller, having a diameter of approximately 2 nanometers (nm, where 1 nm = 10-9 m).

  • Cygwin

    Cygwin is an open source collection of tools that allows Unix or Linux applications to be compiled and run on a Windows operating system from within a Linux-like interface.

  • D

    data center

    A data center (or datacenter) is a facility composed of networked computers and storage that businesses and other organizations use to organize, process, store and disseminate large amounts of data.

  • data center administrator (DCA)

    A data center administrator monitors systems, installs equipment and cabling, and participates in change processes and everyday procedures that support information technology.

  • data center as a service (DCaaS)

    A data center as a service (DCaaS) provider will supply turnkey physical data center facilities and computing infrastructure (e.g., servers, networking, storage, and so on) to clients in the form of a service.

  • data center chiller

    A data center chiller is a cooling system used in a data center to remove heat from one element and deposit it into another element. Chillers are used by industrial facilities to cool the water used in their heating, ventilation and air-conditioning (HVAC) units. (Continued...)

  • data center evaporative cooling (swamp cooling)

    Evaporative cooling, also known as swamp cooling, is a strategy for cooling air that takes advantage of the drop in temperature that occurs when water that's exposed to moving air begins to change to gas. You've probably experienced the effects of evaporative cooling if you've ever changed out of wet clothes because you felt chilled.

  • Data Center Infrastructure Efficiency (DCiE)

    Data Center Infrastructure Efficiency (DCiE) is a metric used to determine the energy efficiency of a data center. The metric, which is expressed as a percentage, is calculated by dividing IT equipment power by total facility power.

  • data center resiliency

    Data center resiliency is the ability of a server, network, storage system, or an entire data center, to continue operating even when there has been an equipment failure, power outage or other disruption.

  • data center services

    Data center services is a collective term for all the supporting components necessary to the proper operation of data center. This includes all the implementation, maintenance and operation of a data center.

  • data integrity

    Data integrity is the assurance that digital information is uncorrupted and can only be accessed or modified by those authorized to do so. Integrity involves maintaining the consistency, accuracy and trustworthiness of data over its entire life cycle.

  • DB2

    DB2 is a family of relational database management system (RDBMS) products from IBM that serve a number of different operating system platforms.

  • Debian

    Debian is a popular and freely-available computer operating system that uses the Linux kernel and other program components obtained from the GNU project.

  • distribution

    In marketing, distribution is the process of moving a product from its manufacturing source to its customers. In computer software, distribution is the phase that follows packaging.

  • DRBD (Distributed Replicated Block Device)

    DRBD (Distributed Replicated Block Device) is a Linux-based software component that facilitates the replacement of shared storage systems by networked mirroring. DRBD makes it possible to maintain consistency of data among multiple systems in a network. DRBD also ensures high availability (HA) for Linux applications... (Continued)

  • ducting (data center cooling)

    Ducting is the use of a metal or plastic pipe to carry air from one place to another.

  • E

    e-cycling

    E-cycling is the practice of reusing, or distributing for reuse, electronic equipment and components rather than discarding them at the end of their life cycle.

  • e-waste

    E-waste is any refuse created by discarded electronic devices and components as well as substances involved in their manufacture or use.

  • economizer

    An economizer is a mechanical device used to reduce energy consumption. Economizers recycle energy produced within a system or leverage environmental temperature differences to achieve efficiency improvements. (Continued...)

  • edge data center

    Edge data centers are small data centers that are located close to the edge of a network.

  • Electric plugs for each country

    Electrical plugs and voltages for different countries around the world.

  • Electronic Data Interchange (EDI)

    Following specific standards, EDI is a way for businesses to securely transfer important data, such as invoices and purchase orders, via the Internet.

  • Emergency Power Off (EPO) button

    The Emergency Power Off (EPO) button -- sometimes called an EPO switch -- is a large red device in data centers that kills power to a particular piece of equipment, or to an entire facility, in the event of an emergency.

  • enclave

    In IBM's OS/390 operating system, an enclave is a representation of a business transaction or unit of work.

  • Energy Star

    Energy Star is a government-backed labeling program that helps people and organizations save money and reduce greenhouse gas emissions by identifying factories, office equipment, home appliances and electronics that have superior energy efficiency. (Continued...)

  • Enterprise Identity Mapping (EIM)

    Enterprise Identity Mapping (EIM) is an open architecture from IBM for helping an enterprise manage the multiple user registries and identities that enable a computer user to access multiple applications with a single sign-on.

  • epoch

    In a computing context, an epoch is the date and time relative to which a computer's clock and timestamp values are determined.

  • ESCON (Enterprise Systems Connection)

    ESCON (Enterprise Systems Connection) is a marketing name for a set of IBM and vendor products that interconnect S/390 computers with each other and with attached storage, locally attached workstations, and other devices using optical fiber technology and dynamically modifiable switches called ESCON Directors.

  • Evaluation Assurance Level (EAL)

    The Evaluation Assurance Level (EAL) is a grade assigned to an IT product or system after completing a Common Criteria security evaluation.

  • event forwarding

    Event forwarding is the transmission of information to a centralized computer concerning events that take place on remote computers or servers... (Continued)

  • What is edge computing? Everything you need to know

    Edge computing is a distributed information technology (IT) architecture in which client data is processed at the periphery of the network, as close to the originating source as possible.

  • F

    Fedora

    Fedora is a popular open source Linux-based operating system.

  • field-replaceable unit (FRU)

    In electronic hardware, particularly computer systems, a field-replaceable unit (FRU) is a circuit board or part that can be quickly and easily removed and replaced by the user or by a technician without having to send the entire product or system to a repair facility.

  • free cooling

    Free cooling is an approach to lowering the air temperature in a building or data center by using naturally cool air or water instead of mechanical refrigeration.

  • fuel cell

    A fuel cell is an electrochemical cell that derives its energy from combustible substances such as hydrogen, methane, propane, methanol, diesel fuel or even gasoline... (Continued)

  • G

    GNOME (GNU Network Object Model Environment)

    GNOME (GNU Network Object Model Environment, pronounced gah-NOHM) is a graphical user interface (GUI) and set of computer desktop applications for users of the Linux computer operating system.

  • GNU General Public License (GNU GPL or simply GPL)

    The GNU General Public License, often shortened to GNU GPL (or simply GPL), lists terms and conditions for copying, modifying and distributing free software.

  • GNU Linux

    The GNU Linux project was created for the development of a Unix-like operating system that comes with source code that can be copied, modified, and redistributed... (Continued)

  • green computing

    Green computing is the use of computers and related resources in an environmentally responsible manner. This involves the implementation of energy-efficient central processing units (CPUs), servers and peripherals as well as proper disposal of electronic waste (e-waste)... (Continued)

  • green data center

    A green data center is a repository for the storage, management, and dissemination of data in which the mechanical, lighting, electrical and computer systems are designed for maximum energy efficiency and minimum environmental impact... (Continued)

  • grid computing

    Grid computing uses small, distributed resources from servers and PCs to solve big problems. But will this architecture survive the cloud era?

  • gzip (GNU zip)

    Gzip (GNU zip) is a free and open source algorithm for file compression. The software is overseen by the GNU project.... (Continued)

  • H

    hard drive overwriter

    In e-cycling, a hard drive overwriter is a program or utility that repeatedly overwrites the data on a computer's hard drive with gibberish.

  • hardware clustering

    Hardware clustering (sometimes called operating system clustering) is a hardware-based method of turning multiple servers into a cluster (a group of servers that acts like a single system).

  • Heartbeat

    Heartbeat is a program that runs specialized scripts automatically whenever a system is initialized or rebooted. Originally designed for two-node Linux-based clusters, Heartbeat is extensible to larger configurations... (Continued)

  • high availability (HA)

    High availability (HA) is the ability of a system or system component to be continuously operational for a desirably long length of time.

  • High Level Assembler (HLASM)

    High Level Assembler (HLASM) is IBM's assembler programming language and the assembler itself for the IBM z/OS, z/VM, OS/390, MVS, VM, and VSE operating systems. Released in June 1992, HLASM was the first new assembler language from IBM in twenty years. Version 4 was released in September 2000.

  • high-performance computing (HPC)

    High-performance computing (HPC) is the use of parallel processing for running advanced application programs efficiently, reliably and quickly. The term applies especially to systems that function above a teraflop or 1012 floating-point operations per second... (Continued)

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