NET/MASTER Management Services (MS) System Management Guide

Configuring Application Process Persistency
Configuring the Processing Environment
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Second, if a persistent application process fails, there is an unavoidable time between
process failure and restart. There is a period of time in which the functions normally
performed by the failed process are not performed. By configuring application
process persistency, your aim is to reduce the time between process failure and restart
as much as possible.
Note BK, EM, and NC processes can also run as process pairs. See “Running BK, EM, and NC Processes as
Process Pairs,” later in this section, for more information.
Results of Application
Process Failure
If a BK process fails, the BSYS, BMON, BLOG, and LOGP virtual users and their
background processing environments supported by the BK process are unavailable.
The virtual users stop performing their functions until the NCP restarts the BK
process.
If an EM process fails, the EMSP virtual user and its background processing
environment are unavailable. NonStop NET/MASTER MS stops receiving EMS
messages from the EMS distributor. When the NCP restarts the EM process, EMS
message flow is reestablished. No messages are lost but messages are resent from
slightly before the last message processed before the failure. There is time between
losing and reestablishing contact between NonStop NET/MASTER MS and the EMS
distributor.
If an IS process fails while controlling an INMC link to a remote system, the INMC
link is disconnected, ISR message flow is disabled, and users logged on to the remote
system (using ROC) are logged off. When the NCP restarts the IS process, the INMC
link is reestablished, ISR message flow is enabled, and users are logged on to the
remote system again automatically. There is time between losing and reestablishing
services between the local and remote systems.
If an MS process fails while a user is logged on, NonStop NET/MASTER MS
automatically logs the user off, restarts the MS process, and displays the logon screen
on the user’s terminal screen. There is time between logging the user off and
displaying the logon screen for the user to log on again.
Finally, if an NC process fails, all NonStop NET/MASTER MS functions supported by
the NC process are temporarily unavailable while the NC process is restarted. The
effect of NC process failure depends on the operating mode in which the NC process is
running, as described next in “Operating Modes and Persistency.”
Operating Modes and
Persistency
The operating mode you choose to run NonStop NET/MASTER MS affects application
process persistency.
Basic Mode
The effect of process failure is most severe in basic mode, in which one static or
dynamic NC process performs all application process functions. Although the NC
process uses fewer resources than those required for either extended basic or
advanced mode, process recovery is relatively slow. Additionally, all application