NonStop Systems Introduction

Glossary
NonStop Systems Introduction—527825-001
Glossary-8
power-fail interrupt
power-fail interrupt . A processor function that interrupts the current instruction stream,
when a power failure occurs, in order to invoke a power-fail interrupt handler. This
interrupt handler provides an orderly shutdown sequence that preserves the existing
state of processor memory for subsequent resumption of operation when power is
restored. See also ride-through power backup.
primary process. The currently active process of a process pair managed by the NonStop
Kernel. See also backup process and process pair.
process. (1) A unique execution of a program in the Guardian environment. (2) An entity in
the Open System Services environment consisting of an address space, a single
thread of control that executes within that address space, and the system resources
required by that thread of control.
process management. The managing of online transaction processing applications on
multiple NonStop systems. Process management functions include configuration and
initialization of processes, monitoring and stopping of processes, and recovery of failed
processes.
process pair. A fault-tolerant arrangement of processes in the Guardian environment
whereby two processes (usually in separate processors) share the same name and
execute identical code. One process functions as the primary process and the other
functions as the backup process. The two processes are synchronized through
checkpoint messages sent from the primary to the backup process. If the primary
process fails, the backup process becomes the primary and continues the application
work from the last valid checkpoint message.
processor. A single central processing unit in a NonStop system or network of systems. A
single system can contain from 2 to 16 processors.
program. A sequence of instructions that can be executed on a computer.
protocol. A set of rules governing the operation of communicating entities. Protocols define
the order in which messages are sent and how the recipient behaves on receipt of the
message. Examples of protocols are TCP/IP, SCSI, ATM, and IIOP.
RDF. See Remote Database Facility (RDF).
reduced instruction-set computing (RISC). A processor architecture based on a relatively
small and simple instruction set, a large number of general-purpose registers, and an
optimized instruction pipeline that supports high-performance instruction execution.
Remote Database Facility (RDF). A software utility that enables disaster tolerance for
production databases, monitors database updates audited by TMF on a source
system, and applies those updates to a copy of the database on a target system.
requester. A process or program that runs in the Guardian environment on a NonStop
system and requests services form a server process. See also client, server, and
requester-server model.