e record is always a hierarchic tree structure of segments. All of the segments that exist hierarchically dependent to a given root segment and that root segment. See also database record.
logical data group
A collection of data elements that gathers database system monitoring information for a specific scope of database activity. The snapshot monitor and event monitor each has its own sets of logical data groups. See also monitor element.
logical data model
The data model that captures the business definition of information assets by using the entity-relationship modeling approach. The logical data model consists of a set of related entities and their business associations. The logical data model can be represented graphically in the logical data model diagram. The logical data model contains logical entities, logical relationships, entity generalization hierarchies, and logical domains.
logical data stream (LDS)
In bidirectional text representation, a stream of data that is organized in a readable sequence. See also visual data stream.
A derivation from a physical document that can have additional service description metadata allocated to the derivation. See also logical model.
- A file for conducting input or output with a physical device.
- A file for mapping user I/O between virtual and real devices.
- A set of input or output operations for a physical or virtual device. For example, the Router logical device has logical device operations for creating a route and removing a route. Logical devices can be an abstraction of a physical device, such as a router, or virtual device, such as a software product.
- The facilities of a logical subsystem with which a host communicates when performing I/O operations to a single addressable unit over an I/O interface. The same logical device may be accessible over more than one I/O interface.
logical device component (LDC)
A subcomponent (for example, a printer or a console) configured with a 3601, 3770 batch, 3770, 3790 batch or LU Type4 terminal. Each subcomponent is handled by BMS output commands as if it is a separate terminal.
logical device operation
A generic instruction for a logical device that is independent of its implementation. For example, a logical device operation to add an IP address applies to all operating systems, but the steps for performing this instruction on each operating system are defined by workflows in a device driver for the operation system. See also logical management operation.
A drain on a logical partition of a nonpartitioning index. See also drain.
- See volume.
- A unit of virtual storage that is made available to the network through virtual logical unit numbers (VLUNs) and iSCSI client logical-unit number (iLUNs). A logical drive consists of one or more physical disks that are combined using Redundant Array of Independent Disks (RAID) technology.
- A database file that describes how data is to be presented or received from a program. A logical file contains no data, but it defines record formats for one or more physical files. See also physical file.
- A file that is stored in one or more server storage pools, either by itself or as part of an aggregate. See also aggregate, physical file, physical occupancy.
logical file system (LFS)
A level of the file system at which users can request file operations by using a system call. The LFS provides the user with a consistent view of multiple physical file systems and multiple file system implementations.
A component of a user-defined index over XML data that contains XML pattern information specified by the CREATE INDEX statement. See also physical index.
In NCP, the representation of the connection between NCP and a node communicating with NCP over a physical line such as token-ring or frame-relay. A single physical line can support multiple logical lines. See also physical line.
- A pair of link stations, one in each of two adjacent nodes, and their underlying link connection, providing a single link-layer connection between the two nodes.
- In a multisystem environment, the means by which a phys