NonStop NS-Series Operations Guide (H06.12+)

5 Processes: Monitoring and Recovery
• “When to Use This Section” (page 71)
• “Types of Processes” (page 71)
— “System Processes” (page 71)
— “I/O Processes (IOPs)” (page 71)
— “Generic Processes” (page 71)
• “Monitoring Processes” (page 72)
— “Monitoring System Processes”
— “Monitoring IOPs”
— “Monitoring Generic Processes”
• “Recovery Operations for Processes” (page 75)
• “Related Reading” (page 75)
When to Use This Section
This section provides basic information about the different types of processes for Integrity
NonStop servers. It gives a brief example of monitoring each type of process and provides
information about the commands available for recovery operations.
Types of Processes
Three types of processes are of major concern to a system operator of an Integrity NonStop
NS-series server:
• System processes
• I/O processes (IOPs)
• Generic processes
System Processes
A system process is a privileged process that is created during system load and exists continuously
for a given configuration for as long as the processor remains operable. Examples of system
processes include the memory manager, the monitor, and the I/O control processes.
I/O Processes (IOPs)
An I/O process (IOP) is a system process that manages communications between a processor
and I/O devices. IOPs are often configured as fault-tolerant process pairs, and they typically
control one or more I/O devices or communications lines. Each IOP is configured in a maximum
of two processors, typically a primary processor and a backup processor.
An IOP provides an application program interface (API) that allows access to an I/O interface.
A wide area network (WAN) communications line is an example of an I/O interface. IOPs
configured using the SCF interface to the WAN subsystem manage the input and output functions
for the ServerNet wide area network (SWAN) concentrator. Examples of IOPs include, but are
not limited to, line-handler processes for Expand and other communications subsystems.
Generic Processes
Generic processes are configured by the SCF interface to the Kernel subsystem. They can be
configured in one or more processors. Although sometimes called system-managed processes,
generic processes can be either system processes or user-created processes. Any process that can
be started from a TACL prompt can be configured as a generic process. Generic processes can
be configured to have persistence; that is, to automatically restart if stopped abnormally.
When to Use This Section 71