NonStop System Glossary

donor system

The computer system you make smaller by removing enclosures, either to reduce the system or to

add the removed enclosures to another target system, using a process known as system reduction.

double-high stack

A stack that includes a base, a frame, and two NonStop S-series system enclosures. Contrast with

single-high stack.

double-wide plug-in card (PIC)

A large-form-factor plug-in card (PIC) that occupies two adjacent PIC slots within a ServerNet

adapter or a NonStop cluster switch. See also single-wide plug-in card (PIC).

download

The process of transferring software from one location to another, where the transferring entity

initiates the transfer.

download line task

Any task running under the Portable Silicon Operating System (pSOS) system product, such as a

data protocol.

downtime

Time during which a computer system is not capable of doing useful work because of a planned

or unplanned outage. From the end user’s perspective, downtime is any time a needed application

is not available.

downward compatibility

The ability of a requester to operate with a server of an earlier revision level. In this case, the

requester is downward-compatible with the server, and the server is upward-compatible with the

requester. Contrast with upward compatibility.

DRAM

Dynamic random-access memory.

drive

See disk drive or tape drive.

dropout

A voltage loss of very short duration (that is, milliseconds).

DSC

See Dynamic System Configuration (DSC).

DSM

See Distributed Systems Management (DSM).

DSM/SCM

See Distributed Systems Management/Software Configuration Manager (DSM/SCM).