IBM 990 manual EMIF. See Escon Multiple Image Facility

6947glos.fm Draft Document for Review April 7, 2004 6:15 pm

core. (1) In an optical cable, the central region of an optical fiber through which light is transmitted. (2) In an optical cable, the central region of an optical fiber that has an index of refraction greater than the surrounding cladding material. See also cladding and optical fiber.

coupler. In an ESCON environment, link hardware used to join optical fiber connectors of the same type. Contrast with adapter.

CPC. Central Processor Complex

CTC. (1) Channel-to-channel. (2) Mnemonic for an ESCON channel attached to another ESCON channel.

CVC. Mnemonic for an ESCON channel attached to an IBM 9034 convertor. The 9034 converts from ESCON CVC signals to parallel channel interface (OEMI) communication operating in block multiplex mode (Bus and Tag). Contrast with CBY.

DDM. See disk drive module.

dedicated connection. In an ESCON Director, a connection between two ports that is not affected by information contained in the transmission frames. This connection, which restricts those ports from communicating with any other port, can be established or removed only as a result of actions performed by a host control program or at the ESCD console. Contrast with dynamic connection. Note: The two links having a dedicated connection appear as one continuous link.

default. Pertaining to an attribute, value, or option that is assumed when none is explicitly specified.

destination. Any point or location, such as a node, station, or a particular terminal, to which information is to be sent.

device address. In the ESA/390 architecture and the z/Architecture, the field of an ESCON or FICON (FC mode) device-level frame that selects a specific device on a control-unit image.

device number. (1) In the ESA/390 architecture and the z/Architecture, a four-hexidecimal-character identifier, for example 19A0, that you associate with a device to facilitate communication between the program and the host operator. (2) The device number that you associate with a subchannel that uniquely identifies an I/O device.

device. A mechanical, electrical, or electronic contrivance with a specific purpose.

direct access storage device (DASD). A mass storage medium on which a computer stores data.

disconnected. In an ESCON Director, the attribute that, when set, removes a dedicated connection. Contrast with connected.

disk drive module (DDM). A disk storage medium that you use for any host data that is stored within a disk subsystem.

Disk. A physical or logical storage media on which a computer stores data (is also sometimes referred to as a magnetic disk).

distribution panel. (1) In an ESCON or FICON environment, a panel that provides a central location for the attachment of trunk and jumper cables and can be mounted in a rack, wiring closet, or on a wall.

duplex connector. In an ESCON environment, an optical fiber component that terminates both jumper cable fibers in one housing and provides physical keying for attachment to a duplex receptacle.

duplex receptacle. In an ESCON environment, a fixed or stationary optical fiber component that provides a keyed attachment method for a duplex connector.

duplex. Pertaining to communication in which data or control information can be sent and received at the same time. Contrast with half duplex.

dynamic connection. In an ESCON Director, a connection between two ports, established or removed by the ESCD and that, when active, appears as one continuous link. The duration of the connection depends on the protocol defined for the frames transmitted through the ports and on the state of the ports. Contrast with dedicated connection.

dynamic connectivity. In an ESCON Director, the capability that allows connections to be established and removed at any time.

Dynamic I/O Reconfiguration. A S/390 function that allows I/O configuration changes to be made non-disruptively to the current operating I/O configuration.

EMIF. See ESCON Multiple Image Facility.

Enterprise System Connection (ESCON). (1) An ESA/390 computer peripheral interface. The I/O interface uses ESA/390 logical protocols over a serial interface that configures attached units to a communication fabric. (2) A set of IBM products and services that provide a dynamically connected environment within an enterprise.

Enterprise Systems Architecture/390® (ESA/390).

An IBM architecture for mainframe computers and peripherals. Processors that follow this architecture include the S/390 Server family of processors.

254IBM eServer zSeries 990 Technical Guide