Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-19
physical outage class
down. Configuring phantom devices is one way you can plan for future growth. Disk
drives are commonly configured as phantom devices.
physical outage class. An outage class that includes physical faults or failure in the
hardware. Any type of hardware component failure belongs in this category.
planned outage. Time during which the system is not capable of doing useful work because
of a planned interruption. A planned outage can be time when the system is brought
down to allow for servicing, upgrades, backup, or general maintenance.
PNA. See Programmatic Network Administrator (PNA).
power-fail testing. The process of testing a software product to ensure that it performs as
specified when power is turned off to various parts of the system.
primary process. The currently active process of a process pair on an HP NonStop system.
See also backup process and process pair.
printing distributor. An EMS distributor process that obtains formatted text for select event
messages and distributes the text to a printer, another display device, or to a file. See
also Event Management Service (EMS), consumer distributor, and forwarding
distributor.
problem management. Activities that provide support for resolving problems in a
production environment. One of the operations disciplines in the operations-
management model.
process. A unique execution of a program.
process monitor. A process that controls the execution of other processes and restarts
them if they stop.
process pair. A fault-tolerant arrangement of processes in the Guardian environment,
whereby two processes 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 kept synchronized through checkpoint
messages sent from the primary to the backup process. If the primary process fails, the
backup process is notified that it is now the primary, and it resumes the application
work from the last valid checkpoint message. See also backup process and primary
process.
process replication. Multiple copies of the same program are concurrently executed to
provide parallelism and availability. If one process stops, one of the other processes
can perform the work of the stopped process.
Programmatic Network Administrator (PNA). An HP product that supports automated
subsystem management.
Queue Manager. An HP product that provides transaction protected queues.