SNIA Online Dictionary

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e-discovery	[Legal] Short for electronic discovery.
EAL	[Data Security] Acronym for Evaluation Assurance Level.
EAMR	[Hardware] Acronym for energy assisted magnetic recording.
EB	[General] Shorthand for exabyte.
Ebit	[General] Shorthand for exabit.
Ebyte	[General] Shorthand for exabyte.
ECC	[Data Communication], [Storage System] Acronym for error correcting code.
economizer	[Management], [Energy] [Energy] Heat exchanger technology used to leverage colder external air to provide data center cooling. Dry side economizers use cooler outdoor air; wet side economizers use cooling towers or chillers. [Management] An accountant that prevents the use of new technology. (e.g. commonly uses the phrase “It’s out of budget or too expensive”).
EE_credit	[Fibre Channel] A credit scheme used to manage end-to-end flow control during the exchange of frames between two communicating devices using Class 2 service.
effective capacity	[Storage System] The amount of data stored on a storage system, plus the amount of unused formatted capacity in that system. This measure is normally used on systems employing space optimization technologies. On these systems, there is no way to precisely predict the effective capacity.
egress routing function	[Fibre Channel] An entity within a Routing Function that performs the egress routing function role.
egress routing function role	[Fibre Channel] A process within a Routing Function that validates the frame, translates the S_ID, and then forwards the frame to the Native Fabric.
EiB	[General] Shorthand for exbibyte.
Eibit	[General] Shorthand for exbibit.
electronic discovery	[Legal] Discovery that includes the identification, preservation, collection, processing, review, analysis, or production of Electronically Stored Information. [ISO/IEC 27050-1] Although electronic discovery is often considered a legal process, its use is not limited to the legal domain.
Electronically Stored Information	[Legal] Data or information of any kind and from any source, whose temporal existence is evidenced by being stored in, or on, any electronic medium. [ISO/IEC 27040] Electronically Stored Information (ESI) includes traditional e-mail, memos, letters, spreadsheets, databases, office documents, presentations, and other electronic formats commonly found on a computer. ESI also includes system, application, and file-associated metadata (3.26) such as timestamps, revision history, file type, etc. Electronic medium can take the form of, but is not limited to, storage devices and storage elements.
embedded controller	[Storage System] A controller that is a non-removable component within a larger system.
embedded storage controller	[Storage System] An embedded controller that exclusively performs storage functions.
Emerald	[Storage System] SNIA Emerald™ Power Efficiency Measurement Specification or SNIA Emerald™ Program.
Emerald Specification	[Storage System] SNIA Emerald™ Power Efficiency Measurement Specification [ISO/IEC 24091:2019]. Defines a uniform taxonomy of storage subsystems and a standard way of measuring power efficiency of the storage subsystems defined in the taxonomy. For more detailed information, please consult the SNIA Emerald Program website (https://www.snia.org/emerald).
Encapsulating Security Payload	[Data Security] A component of IPsec that permits the specification of various confidentiality mechanisms.
encoding	Process of generating transmission characters from data bytes.
encryption	[Data Security] Reversible operation by a cryptographic algorithm converting data into ciphertext so as to hide the information content of the data [ISO/IEC 9798-1:2010]
Enc_Header	[Fibre Channel] An encapsulation header used for forwarding FC frames from a source Routing Function to a destination Routing Function.
End-of-frame	[Fibre Channel] A sequence of bits that delineate the end of a frame.
end-to-end encryption	[Data Security] Encryption of information at its origin and decryption at its intended destination without intermediate decryption.
end-to-end flow control	[Network], [Fibre Channel] 1. [Network] Control of message flow between the two end parties of a communication on a network. 2. [Fibre Channel] Flow control that occurs between two communicating Fibre Channel Nx_Ports.
end-to-end flow control buffer	[Fibre Channel] A buffer associated with end-to-end flow control.
end-to-end security	[Data Security] Safeguarding information in an information system from point of origin to point of destination. [CNSSI-4009]
energy assisted magnetic recording	[Hardware] A recording technique that directs energy at the media to aid the recording process of an HDD.
energy efficiency	[Computer System] The power efficiency of a system over time. While power and energy efficiency look about the same to a layman, the numbers may be different (even neglecting the units) on account of temporal variations in supply voltages, power and load factors and so on.
Enhanced Transmission Selection	[Network] A Data Center Bridging component that specifies a frame scheduling mechanism to support the allocation of data transmission capacity amongst traffic classes that share a link.
ENode	[Network], [Fibre Channel] Synonym for FCoE Node.
ENode MAC address	[Fibre Channel] The MAC address used by the ENode during the FCoE Initialization Protocol.
Enterprise Resource Management	[Management], [Network] Software that manages all aspects of an organization's assets, systems, services and functions. ERM systems manage a set of resources in the wider perspective of an organization's entire business. Managing in an enterprise context requires that entities be named uniquely and locatable within the enterprise, that heterogeneity of platforms and services may be assumed, and that the dynamic nature of the environment is taken into account.
Enterprise Systems Connection	[Storage System] A serial I/O interconnect used on data center mainframes. Similar to Fibre Channel in many respects, ESCON is based on redundant switches to which computers and storage subsystems connect using serial optical connections.
entropy	[Data Security] A measure of the amount of uncertainty that an attacker faces to determine the value of a secret. [NIST SP 800-63] The value is sometimes measured in bits of security strength, where a value of 0 indicates no security strength (i.e., full predictability or no randomness) and a positive value indicates increasing security strength.
entry/exit slot	[Storage System] A location in a library through which a removable volume can be inserted or removed.
EOF	[Fibre Channel], [File System] 1. [Fibre Channel] Abbreviation for End-of-Frame. 2. [File System] A designation or marker for the end of a file.
erasure coding	[Data Recovery] An error correcting coding technology.
ERM	[Management], [Network] Acronym for Enterprise Resource Management.
Error Correcting Code	[Data Communication], [Storage System] A scheme for checking the correctness of data and correcting errors in that data.
ESCON	[Storage System] Acronym for Enterprise Systems Connection.
ESI	[Legal] Acronym for Electronically Stored Information.
ESP	[Data Security] Acronym for Encapsulating Security Payload.
Ethernet	[Network] A local area networking technology based on packetized transmissions between physical ports over a variety of electrical and optical media. Ethernet transports various upper layer protocols, the most popular of which is TCP/IP. Ethernet standards are maintained by the IEEE 802.3 committee.
Ethernet adapter	[Network] An adapter that connects an intelligent device to an Ethernet network, usually called an Ethernet network interface card or Ethernet NIC.
eventual consistency	A behavior of a distributed system that provides consistency over time but does not provide immediate consistency guarantees.
EVSN	[Data Recovery] Acronym for External Volume Serial Number.
Exabit	[General] Shorthand for 1,000,000,000,000,000,000 (1018) bits. See also exbibit.
Exabyte	[General] Shorthand for 1,152,921,504,606,846,976 (260) bytes. Binary notation is commonly used for semiconductor memory sizes. See also exabyte.
Exbibit	[General] Shorthand for 1,152,921,504,606,846,976 (260) bits. Binary notation is most commonly used for semiconductor memory sizes. See also Exabit.
Exbibyte	[General] Shorthand for 1,152,921,504,606,846,976 (260) bytes. Binary notation is most commonly used for semiconductor memory sizes. See also Exabyte.
Exchange	[Fibre Channel] A set of one or more non-concurrent related Sequences passing between a pair of Fibre Channel ports. An Exchange encapsulates a "conversation". Exchanges may be bidirectional and may be short or long lived.
Exchange Status Block	[Fibre Channel] A data structure that contains the state of an Exchange. An originator FC_Port has an Originator Exchange Status Block for each concurrently active Exchange and a responder FC_Port has a Responder Exchange Status Block for each concurrently active Exchange.
Exchange_Identifier	[Fibre Channel] A generic term denoting either an Originator Exchange Identifier (OX-ID) or a Responder Exchange Identifier (RX_ID).
expansion card	[Computer System] A term for optional adapters in the form of printed circuit modules that can be added to intelligent devices. Expansion cards include host bus adapters, network interface cards, NVRAM, and other special purpose adapters.
expansion module	[Computer System] Synonym for expansion card.
expansion slot	[Computer System] A mounting and internal bus attachment point within an intelligent device into which expansion cards are able to be inserted.
expired data	[Data Management] Data that is no longer required to be retained for any reason. Data may become expired data when it has reached its defined retention period or when an event makes it obsolete and it has no further value to the organization becoming a candidate for permanent deletion. See disposition policy.
explicit addressing	[Storage System] A form of addressing in which the data's address is explicitly specified in the access request. See implicit addressing.
exploit	[Data Security] A defined way to breach the security of an IT system through a vulnerability.
export	[Computer System] 1. To cause to appear or make available. 2. To move objects, such as data, from within a system to a location outside the system, usually requiring a transformation during the move. Disk array control software exports virtual disks to its host environment. In file systems, a directory may be exported or made available for access by remote clients. 3. [legal] To move across international borders.
extended file attribute	[File System] An element of file metadata.
Extended_Header	[Fibre Channel] A sequence of words that may be present in a frame between the SOF delimiter and the Frame_Header to support frame handling functions not enabled by the Frame_Header.
eXtensible Access Method	[Standards] An interface standardized by the SNIA that provides applications with standard methods for storing data and associated metadata on fixed content storage. The eXtensible Access Method (XAM) Application Programming Interface (API) is standardized by SNIA.
eXtensible Markup Language	[Standards] A universal format for structured documents and data on the World Wide Web. The World Wide Web Consortium is responsible for the eXtensible Markup Language (XML) specification. See www.w3.org.
extent	[Storage System] 1. A set of consecutively addressed blocks that is allocated to a single file. 2. A set of consecutively located tracks on a CKD disk that is allocated to a single file. 3. A set of consecutively addressed blocks that is part of a single virtual disk. A single storage device may be organized into multiple extents of different sizes, and may have multiple (possibly) non-adjacent extents that are part of the same virtual disk-to-member disk array mapping. This type of extent is sometimes called a logical disk.
external controller	[Storage System] An intelligent controller that exists outside the host computer enclosure and attaches via external connections.
external disk controller	[Storage System] Synonym for external storage controller.
external storage controller	[Storage System] A type of external controller used to control storage. External storage controllers usually mount in the enclosure containing the disks they control and may be a component of a disk array.
External Volume Serial Number	[Data Recovery] A human-readable volume serial number on a removable volume.
eye	[Data Communication] The center region of an eye diagram that does not occur for correctly formed signals, that distinguishes presence of signal (region above the eye) from absence of signal (region below the eye).
eye diagram	[Data Communication] A diagram used to specify optical or electrical signal transition characteristics for transmitters, in which the horizontal axis represents normalized time from pulse start and the vertical axis represents normalized amplitude.
eye opening	[Data Communication] Quantitative measure of the space in an eye diagram that does not occur for correctly formed signal transitions, and that prevents signal values from incorrectly being identified as high or low.
E_Port	[Fibre Channel] The port within a Fibre Channel Switch that connects to another Fibre Channel Switch via an Inter-Switch Link. E_Ports are used to connect Fibre Channel Switches to form a multi-Switch Fabric.