NonStop System Glossary

directory tree
A hierarchy of directories. In the Open System Services (OSS) environment, directories are connected
to each other in a branching hierarchical fashion such that only one path exists between any two
directories (if no backtracking occurs).
disconnecting means
A device, group of devices, or other means by which the conductors of a circuit can be disconnected
from their source of supply.
discovery
In client software for OSM and TSM, the process of identifying the resources that exist on a NonStop
server. See also incremental discovery and initial discovery.
disk bootstrap
A software entity residing on disk that is used to load the NonStop operating system image
(OSIMAGE) into memory during a system load. A disk that contains the disk bootstrap is referred
to as a bootable disk. The disk bootstrap is placed on the disk either as part of a tape load or as
a result of the SCF CONTROL DISK, REPLACEBOOT command.
disk cache
A temporary storage buffer into which data is read, retained, and perhaps updated before being
written to disk, for more efficient processing.
disk drive
A device that stores and accesses data on a magnetic disk. Random access to addressable locations
on a magnetic disk is provided by magnetic read/write heads. See also DISK object type.
DISK object type
The Subsystem Control Facility (SCF) object type for all disk devices attached to your system.
disk volume
See volume.
DISKGEN
A system generation option that invokes the DISKGEN program to copy directly to disk the files
necessary to generate a NonStop operating system. For G-series RVUs, DISKGEN can be used
instead of a system image tape (SIT).
distributed system
A system that consists of a group of connected, cooperating computers.
Distributed Systems Management (DSM)
A set of tools used to manage NonStop systems and Expand networks.
Distributed Systems Management/Software Configuration Manager (DSM/SCM)
A graphical user interface (GUI)-based program that installs new software and creates a new
NonStop operating system. DSM/SCM creates a new software revision and activates the new
software on the target system.
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