[Data Security] An unauthorized user who attempts to gain and/or succeeds in gaining access to an information system.
[Computer System] To stop all activity in a computer system in an orderly manner.
[File System] A path that provides a different name for a file.
Hard links are independent references to the same file; the file content is not deleted until every hard link to the file is deleted.
[Fibre Channel] A zone consisting of zone members that are permitted to communicate with one another via the fabric.
Hard zones are enforced by fabric switches that prohibit communication among members not in the same zone on a frame by frame basis, based on the source and destination addressing. Well-known addresses are implicitly included in every zone.
[Data Management] A value deterministically derived from data and assumed to be unique enough within the domain of that data for the purposes of its application.
[Storage System] A method of performing data deduplication by calculating and comparing hash values.
[Data Security] A value calculated over the contents of a message (usually using a cryptographic hash algorithm) that can be used to demonstrate that the contents of the message have not been changed during transmission.
[Computer System] Acronym for Host Bus Adapter.
[General] An approximation for a calculation that is too expensive to perform in its entirety.
[Data Management] The automated migration of data objects among storage devices, usually based on inactivity.
Hierarchical storage management is based on the concept of a cost-performance storage hierarchy. By accepting lower access performance (higher access times), one can store objects less expensively. By automatically moving less frequently accessed objects to lower levels in the hierarchy, higher cost storage is freed for more active objects, and a better overall cost to performance ratio is achieved.
[Computer System] The ability of a system to perform its function continuously (without interruption) for a significantly longer period of time than the reliabilities of its individual components would suggest.
High availability is most often achieved through failure tolerance. High availability is not an easily quantifiable term. Both the bounds of a system that is called highly available and the degree to which its availability is extraordinary must be clearly understood on a case-by-case basis.
The subsequent 6400 Mbit per second I/O interface standard, HIPPI-6400, is more commonly referred to as the Gigabyte System Network (GSN) standard.
[Fibre Channel] A form factor that allows quick connect/disconnect for Fibre Channel copper interfaces.
[Network] [Standards] Acronym for High Performance Parallel Interface.
[Data Security] Acronym for Hashed Message Authentication Code.
[Computer System] A host computer.
[Computer System] Synonym for host bus adapter.
[Computer System] Synonym for host I/O interconnect.
Host cache may be associated with a file system or database, in which case, the data items stored in the cache are file or database entities. Alternatively, host cache may be associated with the device driver stack, in which case the cached data items are sequences of disk blocks. See cache, controller cache, disk cache.
[Computer System] Any computer system to which disks, disk subsystems, or file servers are attached and accessible for data storage and I/O.
Mainframes, servers, workstations and personal computers, as well as multiprocessors and clustered computer complexes, are all referred to as host computers in SNIA publications.
The term host environment is used in preference to host computer to emphasize that multiple host computers are being discussed, or to emphasize the importance of the operating system or other software in the discussion.
[Capacity Optimization] Deprecated synonym for source data deduplication.
[Data Recovery] Synonym for online backup.
[Storage] Inserting ranges of addresses that are accessed with greater frequency into a synthetically generated workload.
Hot banding is intended to reward caching behavior on the part of the storage system being measured.
[Storage System] A disk whose capacity to execute I/O requests is saturated by the aggregate I/O load directed to it from one or more applications.
[File System] A frequently accessed file.
[Storage System] A disk being used as a hot standby component.
[Computer System] A redundant component in a failure tolerant subsystem that is powered and ready to operate, but that does not operate as long as all of its target primary components are functioning.
Hot standby components increase storage subsystem availability by allowing systems to continue to function when a component such as a controller fails. When the term hot standby is used to denote a disk, it specifically means a disk that is spinning and ready to be written to, for example, as the target of a rebuilding operation.
[Data Recovery] Acronym for Hierarchical Storage Management.
[Fibre Channel] Acronym for High Speed Serial Direct Connect.
[Standards] Acronym for HyperText Markup Language.
[Standards] Acronym for HyperText Transfer Protocol.
[Network] A communications infrastructure element to which nodes on a multi-point bus or loop are physically connected.
Commonly used in Ethernet and Fibre Channel networks to improve the manageability of connecting devices to a bus structure, both managing physical cables and supporting the addition or removal of nodes from the bus while it is operating. Hubs maintain the logical loop topology of the network of which they are a part, while creating a “hub and spoke” physical star layout. Unlike switches, hubs do not aggregate bandwidth.
Hub ports include loop healing port bypass functions. Some hubs have additional management functionality. There is no definition of a hub port in any Fibre Channel standard.
[Cloud] A composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability.
[Standards] A computer language consisting of a set of tags or “markup” codes that describe how a document is displayed by a web browser.
HTML tags are delimited by the characters "<" and ">". For example, the markup code "<p>" indicates that a new paragraph is beginning, while "</p>" indicates that the current paragraph is ending.