SCF Reference Manual for the Kernel Subsystem

3 Configuring and Managing Generic Processes
This chapter describes how to configure and manage a generic process. A generic process can
be a copy of a program, a program written by a third-party supplier, or a user-written program
that can be started by an explicit or implicit RUN command.
Definition of a Generic Process
A process is a running entity that is managed by the operating system, as opposed to a program,
which is a collection of code and data.
An I/O process (IOP) is a specialized process that performs input and output transfer from one
device to another; for example, between a ServerNet addressable controller and a specific device
type. Other characteristics of an I/O process are:
• An I/O process usually uses privileged code (processes with a nonzero device type).
• An I/O process manages communication with I/O devices, such as disks, printers, and
communication lines.
• An I/O process pair logically owns one or more I/O devices or communication lines.
A generic process is a device-type 0 process that has fewer limitations than an IOP. HP, a third-party
company, or any user can configure a generic process to start in one or more processors. A generic
process:
• Is configured by entering an ADD command that specifies attributes to customize the process.
• Is started and maintained by the $ZPM persistence manager.
• Once it is started, has its persistence managed by the Kernel subsystem; hence, generic
processes are sometimes called system-managed processes.
You can create a generic process to replace any system process that can be started from TACL
and that does not require a PARAM or ASSIGN.
Examples of generic processes created by HP are:
• Subsystem manager processes like $ZZKRN, $ZZSTO, $ZZLAN, and $ZZWAN.
• The $ZHOME process, which allows user processes to survive errors received from the $YMIOP
system console (for example, error 140). This feature is described in the NonStop S-Series
Planning and Configuration Guide, the NonStop S-Series Operations Guide, or the NonStop
Operations Guide (for J- and H-series RVUs). See the INFO display of the $ZHOME process.
The commands for control and management of generic processes are described in Chapter 6: SCF
Commands for the Kernel Subsystem (page 73). They are:
ABORT, ADD, ALTER, DELETE, and STARTControl commands:
INFO, NAMES, STATUS, and VERSIONManagement commands:
Characteristics of a Generic Process
Generic processes have these characteristics:
• You can configure a generic process like a Pathway server class, to start in one processor,
more than one processor, or in each processor in the system. See “Controlling Where a
Generic Process Starts” (page 43).
• You can control when a generic process should start and, optionally, restart. See “Controlling
When a Generic Process Starts” (page 43).
38 Configuring and Managing Generic Processes