6760 ServerNet/DA Manual

Glossary
6760 ServerNet/DA Manual—424879-003
Glossary-22
DID
DID. See destination ServerNet ID (DID).
DIMM. See dual inline memory module (DIMM).
direct current (dc). Electric current that flows in only one direction. Contrast with alternating
current (ac).
directory. A type of Open System Services (OSS) special file that contains directory entries,
which associate names with files. No two directory entries in the same directory have
the same name.
directory entry. In the Open System Services (OSS) file system, an object that associates
a filename with a file. Several directory entries can associate names with the same
file. See also link
.
directory loop. In the Open System Services (OSS) file system, an error condition in which
a directory is identified as its own parent directory.
directory special file. See directory.
directory stream. In the Open System Services (OSS) file system, an object with an
opaque data type. A process can sequentially read directory entries from a directory
stream.
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. For the Compaq TSM package, the process of identifying the resources that
exist on an HP NonStop™ S-series server. See also incremental discovery
and initial
discovery.
disk bootstrap. A software entity residing on disk that is used to load the HP NonStop™
Kernel 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 disk. There are two types of disk
drives: magnetic and optical. Random access to addressable locations on a magnetic
disk is provided by magnetic read/write heads. Random access to addressable
locations on an optical disk is provided by a low-intensity laser. See also volume
.