This glossary defines terms and abbreviations in this publication.
Some of the definitions are taken from other glossaries. The letters in the parentheses that follow some definitions indicate the source of the definition:
(A) The American National Standard Dictionary for Information Systems, ANSI X3.172-1990, copyright 1990 by the American National Standards Institute (ANSI).
(E) The ANSI/Electronic Industries Association (EIA) Standard-440-A, Fiber Optic Terminology.
(I) The Information Technology Vocabulary, developed by Subcommittee 1, Joint Technical Committee 1, of the International Organization for Standardization and International Electro-technical Commission (ISO/IEC/JTC1/SC1).
(IBM) The IBM Dictionary of Computing, copyright 1994 by IBM.
(T) Draft international standards committee drafts, and working papers being developed by the ISO/IEC/JTC1/SC1.
An area of the drive and electronics module that is used for SL8500 library electronic and power equipment and for other standard 19-inch rack-mount electronic equipment. Up to four racks are permitted in the electronics/drive assembly. Rack-mount equipment must be on the approved equipment list.
A character or group of characters that identifies a register, a particular part of storage, or some other data source or destination. (A).
A character or group of characters that identifies a register, a particular part of storage, or some other data source or destination. (A).
A Fibre Channel interconnect topology in which all parts are connected in a common loop. Before transmitting data, devices must participate in arbitration to gain control of the loop.
arbitrated loop physical address (AL_PA)
A one-byte value that identifies a port in an arbitrated loop topology.
Any process by which a user of shared resources negotiates with other users for the right to use the resource. A port connected to a shared bus must win arbitration before it transmits data on the bus.
A command that separates record data from standard labels or other record data. This command only adds the tape mark to the data buffer without data synchronization to the tape media.
The process of connecting two or more Fibre Channel switches together to increase the number of ports or to extend distances.
A functional unit, controlled by the processor (or host), that handles the transfer of data between processor storage and local peripheral equipment. (IBM)
A data cartridge that contains special material to clean the tape path in a transport or drive.
To save space by eliminating gaps, empty fields, redundancy, or unnecessary data to shorten the length of records or files. (IBM)
The manner in which the hardware and software of an information processing system is organized and interconnected. (T)
data path key management (DPKM)
The use of the SCSI 4 commands Security Protocol In and Security Protocol Out to implement host-based key management encryption on StorageTek tape drives.
The speed of a data transfer process, usually expressed in bits per second or bytes per second. (IBM)
A random binary pattern over-writing existing data from the point of an Erase command to the end-of-tape.
A data cartridge formatted for use as a regular data tape for the system in which it is used.
The regions of recorded tape containing user data formed as discreet longitudinal tracks (similar to railroad tracks).
Pertaining to the detection and isolation of errors in programs and faults in equipment.
A drive controls the movement of the tape and records or reads the data on the tape as desired by the customer.
dynamic host configuration protocol (DHCP)
A network protocol that enables a server to automatically assign an IP address to devices on a network. DHCP assigns a number dynamically from a defined range of numbers for a given network.
dynamic world wide name (dWWN)
A feature that applies dynamic names to network devices rather than fixed names. When a dWWN-named device is replaced, it is assigned the same WWN as the one it replaced, preventing reconfiguration of the network.
The use of programming techniques and special machine features to permit a computing system to execute programs written for another system. (IBM)
The translation of data into a secret code. Encryption is one of the most effective ways to achieve data security. To read an encrypted file, you must have access to a special key or password that enables you to decipher it.
A coded character recorded on a data medium to indicate the end of the medium. (IBM)
1. An internal label indicating the end of a file and possible containing data for file control. (T)
2. Synonymous with trailer label.
A marker on a magnetic tape to indicate the end of the permissible recording area. (IBM)
Any of the physical conditions required for the protection and proper operation of a functional unit; the requirement is usually specified as a nominal value and a tolerance range. For a device, there may be more than one set of environmental requirements; for example, one set for transport, another for storage, and another for operation. (T) (A)
To remove data from a data medium, leaving the medium available for recording new data. (I) (A)
A discrepancy between a computed, observed, or measured value or condition and the true, specified, or theoretically correct value or condition. (I) (A)
The Fibre Channel topology similar to a telephone switch in that the initiator of a call to the receiving port simply provides the receiver with the port address, and the fabric routes the transmission to the correct port. A fabric differs from a point-to-point or arbitrated loop topology in that it provides for interconnections between ports without having a point-to-point connection. The fabric also serves as a media-type converter.
A four-character hexadecimal code generated in response to an error to help isolate failures within the device. Some FSCs are for information purposes only.
The branch of optical technology concerned with the transmission of radiant power through fibers made of transparent materials such as glass, fused silica, and plastic. (E)
A cable made of ultra-thin glass or silica fibers which can transmit data using pulses of laser light. Fiber-optic cables have several advantages over copper cables: they have much less signal loss; they allow information to be transmitted at higher speeds and over longer distances; they are not affected by external electrical noise; and they are better for transmissions which require security.
One of several types of devices used to join pairs of optical fibers together.
The National Committee for Information Technology Standards standard that defines an ultrahigh-speed, content-independent, multilevel data transmission interface that supports multiple protocols simultaneously. Fibre Channel supports connectivity to millions of devices over copper or fiber-optic physical media and provides the best characteristics of both networks and channels over diverse topologies.
An ESA/390 and zSeries computer peripheral interface. The I/O interface uses ESA/390 and zSeries FICON protocols (FC-FS and FC-SB-2) over a Fibre Channel serial interface that configures units attached to a FICON-supported Fibre Channel communications fabric.
A channel having a Fibre Channel connection (FICON) channel-to-control-unit I/O interface that uses optical cables as a transmission medium. May operate in either FC or FCV mode.
To prevent the erasure or overwriting of data stored on data cartridges. See also write-protect switch.
A sync operation or command used to force data to tape.
For FICON: The command protocol is a tape mark command without a count field.
For Fibre Channel: The command protocol is not an actual synch command. It is a tape mark command that includes a count field. A count equal to zero indicates a file synch.
An ordered set of instructions and data stored in a way that is functionally independent of main storage; for example, microprograms stored in a ROM. (T) See also microcode.
A special type of fabric port that an arbitrated loop uses to connect N_Ports and NL_Ports into a fabric, thus making a public loop.
A communication protocol that enables signals to be transmitted and received simultaneously.
A 32-bit, or 4-byte, number in dotted decimal format (typically written as four numbers separated by periods, such as 107.4.1.3 or 84.2.1.111) that is applied to an IP Address to identify router interface.
One billion (109) bytes. When referring to disk and tape capacity, one GB equals 1,000,000,000 bytes.
When referring to memory capacity, one GB equals 1,073,741,824 in decimal notation or 230 bytes.
A part of the library robot whose function is to grasp cartridges and move them between storage slots and drives. A camera on the hand assembly reads cartridge volume labels.
All or part of the physical components of an information processing system, such as computers or peripheral devices. (T) (A)
A circuit installed in a multi-platform host or device that interfaces between the device and the bus.
A Fibre Channel Arbitrated Loop switching device that enables multiple servers and targets, such as storage systems, to connect at a central point. A single hub configuration appears as a single loop.
A device that provides a visual or other indication of the existence of a defined state. (T)
A process that activates a machine reset and loads system programs to prepare a computer system for operation. Processors having diagnostic programs activate these programs at initial program load execution. Devices running firmware usually reload the functional firmware from a diskette or disk drive at initial program load execution.
The operations required for setting a device to a starting state, before the use of a data medium, or before implementation of a process. (T)
A protocol used to route data from its source to its destination in an Internet environment. (IBM)
internet protocol v4 (IPv4) address
A four-byte value that identifies a device and makes it accessible through a network. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be from 0 to 255. For example, 129.80.145.23 could be an IP address.
internet protocol v6 (IPv6) address
The next generation internet protocol. It provides a much larger address space than IPv4. This is based upon the definition of a 128-bit address - IPv4 used a 32-bit address. The IPv6 address format is eight fields of four hexadecimal characters separated by colons (for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334)
A standard connector for 2-Gbps or 4-Gbps Fibre Channel data transfer. This type of connector is used on fiber-optic cables.
A robotic system that stores, moves, mounts, and dismounts data cartridges that are used in data read or write operations.
A relationship between a channel and control unit that designates the physical path to be used for device-level communication between each entity, defined by a link address assigned to each entity.
Megabytes or 1,000,000 bytes for disk or tape storage but 1,048,576 (220) bytes of memory capacity.
A list of options displayed to the user by a data processing system, from which the user can select an action to be initiated. (T)
A code, representing the instructions of an instruction set, that is implemented in a part of storage that is not program-addressable. (IBM)
A graded-index or step-index optical fiber that enables more than one bound mode to propagate. (E) Contrast with single mode.
An optical fiber designed to carry multiple signals, distinguished by frequency or phase, at the same time.
A 32-bit, or 4-byte number, in dotted decimal format (typically written as four numbers separated by periods, such as 255.255.0.0 or 255.255.255.0) that is applied to an IP address to identify the network and node address of a host or router interface. (Synonymous with subnet mask.)
An arrangement of nodes and branches that connects data processing devices to one another through software and hardware links to facilitate information interchange.
A connection that exists between an initiator, a target, and a logical unit. This is where one initiator port talks to one target port, addressing one LUN and together they execute a task.
A port attached to a node for use in the point-to-point arbitrated loop and fabric topologies of Fibre Channel. The NL_Port is configured as a private or a public loop.
Pertaining to the operation of a functional unit when under the direct control of the computer. (T)
A functional unit that contains switches used to control all or part of a computer and possibly the indicators giving information about its functioning. (T)
One of two major factors on which the total productivity of a system depends. Performance is largely determined by a combination of throughput, response time, and availability. (IBM)
A topology in which exactly two ports communicate. In Fibre Channel, the two ports are N_Ports.
A specific communications end point within a host. A port is identified by a port number. (IBM) (2) In Fibre Channel, an access point in a device where a link attaches.
A set of semantic and syntactic rules that determines the behavior of functional units in achieving communication. (I)
The act of overwriting a legacy data cartridge by a newer generation drive. For example, a cartridge written by a T10000A drive can be overwritten (reclaimed) by a T10000B drive while a cartridge written by a T10000B drive can be reclaimed by a T10000A drive.
A standard connector for 1-Gbps Fibre Channel data transfer. This type of connector is used on fiber-optic cable.
Optical fiber in which only the lowest-order bound mode can propagate at the wavelength of interest. (E)
small form-factor pluggable (SFP)
Technology with a 2-gigabit or 4-gigabit transfer speed over smaller connectors, cables, and transceivers for larger bandwidth capability.
In Fibre Channel technology, a device that connects Fibre Channel devices together in a fabric.
A combination of functionally interrelated interacting mechanical and electrical elements designed to work as a coherent entity.
A container holding magnetic tape that can be processed without separating the tape from the container.
A unit of measure equal to one trillion (1012) bytes of disk or tape storage capacity.When referring to memory capacity, one TB equals 1,099,511,627,776 in decimal notation or 240 bytes.
transmission control protocol/internet protocol (TCP/IP)
A set of communication protocols that support peer-to-peer connectivity functions for both local and wide area networks. (IBM)
To change the status of a device from online to offline. When a device is offline, no data set may be opened on that device. (IBM)
A software application that enables a user to monitor and perform some operations on one or more tape drives remotely.
VolSafe (volume safe) is a special feature that provides write once, read many (WORM) technology to VolSafe-designated tape cartridges. VolSafe permits new data to only append the tape media, while it prevents erasure or overwrite of previously written data.
An alphanumeric label that the host software uses to identify a volume. It attaches to the spine of a cartridge and is both human- and machine-readable.
A 64-bit network address that identifies the company (in IEEE format) with a vendor specific identifier.
A single pass of tape from either BOT to EOT or EOT to BOT with the heads in a fixed transverse location.
A storage classification for media that can be written only once but read many times.
An output operation that sends a processed record to an output device or output file. (IBM)
A setting on data cartridges that prevents data from being written on the tape. Reading data is still possible.
A command that separates record data from standard labels or other record data. This command implies buffered data synchronization to tape media.
For FICON: The command protocol is a tape mark command without a count field.
For Fibre Channel: The command protocol includes a count field. A count field greater than zero indicates ”count” number of physical tape marks must be written to tape.