NET/MASTER Management Services (MS) System Management Guide

Running BK, EM, and NC Processes as Process Pairs
Configuring the Processing Environment
11–50 115414 NonStop NET/MASTER MS System Management Guide
An NCL process uses the NCL START verb to start a persistent NCL process. The
START verb must satisfy two conditions. First, the START verb must specify that the
new NCL process is to run as a persistent NCL process. Second, the START verb must
specify that the new NCL process is to run in a background processing environment.
(The name of the NCL process and any startup parameters passed to the NCL process
are checkpointed to the backup BK, EM, or NC process when the NCL process is
started.) Refer to the NonStop NET/MASTER NCL Reference Manual and the NonStop
NET/MASTER NCL Programmer’s Guide for more information about the syntax and use
of the START verb.
Note A persistent NCL process can only execute in a background processing environment. These
environments are supported only by BK, EM, and NC processes. This means that IS and MS processes,
which do not support the environment in which persistent NCL processes execute, cannot run as process
pairs. Refer to the NonStop NET/MASTER NCL Programmer’s Guide for more information about
background processing environments.
Determining the BK, EM, or
NC Backup Process
The startup configuration for BK, EM, and NC processes cannot include whether to
run these processes as process pairs. This means that the NCP always starts BK, EM,
and NC processes as persistent processes during NonStop NET/MASTER MS startup.
Additionally, the NCP does not have information about these processes as process
pairs. This means that the NCP always regards each BK, EM, and NC process as a
persistent process while NonStop NET/MASTER MS is running, even though a BK,
EM, or NC process may actually be running as a process pair.
The BK, EM, or NC process that is currently running becomes the primary process of
the BK, EM, or NC process pair and starts the backup process.
For a static BK, EM, or NC process started as a process pair, the PARAM
PROCESSCPU command specifies the CPU in which to create the backup process, as
follows:
If the primary process is running in the first CPU, the primary process creates the
backup process in the second CPU, if the CPU is available.
If the primary process is running in the second CPU, the primary process creates
the backup process in the first CPU, if the CPU is available.
If the primary process is not running in either the first or second CPU, the first
CPU is the first preference for creating the backup process and the second CPU is
the second preference, if either CPU is available.
If the preferred CPU is unavailable, the primary process creates the backup
process in the next higher-numbered CPU (selected in a round-robin fashion)
relative to the CPU in which the primary process is currently executing.
If no CPU is available, the primary process creates the backup process when the
appropriate CPU becomes available. Meanwhile, the primary process runs
without a backup process (and will not survive a failure)