IBM 3590 manual Glossary

error-recovery procedures (ERP). (1) Procedures designed to help isolate and, where possible, to recover from errors in equipment. The procedures are often used in conjunction with programs that record the statistics of machine malfunctions. (2) Error-recovery procedures performed by the subsystem.

explicitly activated. A process in which the attributes of an identifier are specified. Contrast with implicitly activated.

extended contingent allegiance. (1) A condition caused by a permanent buffered-write error in which the drive responds only to the channel path group from which the write command was received. The extended contingent allegiance continues until a controlling computer in the channel path group retrieves the unwritten data from the buffer or issues a tape motion command. (2) A condition generated by an initiate recovery message to assist in extended error recovery procedures in multi-initiator systems.

F

Fabric, Fibre Channel. An interconnection that receives addressed information which, in turn, routes the information to its appropriate destination.

FC. Feature code.

Fibre Channel. An optics cable utilizing filaments to transmit data.

Fibre Channel arbitrated loop (FC-AL). In this topology, two or more Fibre Channel end points are interconncted through a looped interface.

Information is routed through the loop to its destination.

Fibre Channel hub. In this topology, the hub provides ports similar to switch ports and uses a Fibre Channel arbitrated loop structure.

Fibre Channel switch (switched fabric). In this topology, two or more end points are interconnected through one or more switches.

Fibre Channel topologies. Shared loop host and storage controllers.

FID. format identification field

fiducial. A reference point which guides the cartridge-handling device to the tape subsystem location.

field replaceable unit (FRU). An assembly that is replaced in its entirety when any one of its components fails. In some cases a field replaceable unit may contain other field replaceable units; for example, a brush and a brush block that can be replaced individually or as a single unit.

file. A set of related records, treated as a unit, for example, in stock control, a file could consist of a set of invoices.

file protected. Pertaining to a tape volume from which data can be read only. Data cannot be written on or erased from the tape.

format. The arrangement or layout of data on a data medium.

FRU. Field replaceable unit.

G

GB. Gigabyte; 1 073 741 824 bytes of storage.

global command. A global command is a command that affects multiple devices in the I/O subsystem in a way that the control program needs to be aware of.

H

host system. A data-processing system that is used to prepare programs and the operating environments for use on another computer or controller.

I

immediate commands. Immediate commands do not transfer data and receive channel end

Glossary 135