IBM AS/400 manual v Mix interactive and batch jobs on a wide area network line

vMix interactive and batch jobs on a wide area network line

vPerformance considerations for AnyNet communications

vSubsystems

Considerations for subsystem configuration for error recovery performance

Each piece of work that runs on the AS/400 system is called a job. Each job is a single, identifiable sequence of processing actions that represents a single use of the system. The basic types of jobs performed are interactive jobs, batch jobs, spooling jobs, autostart jobs, and prestart jobs.

Jobs that run in subsystems do all work that is performed on the AS/400. As the number of users on the system increases, it becomes important for you to consider how the communications and interactive subsystems should be configured.

The configuration of subsystems has little impact in normal data path operations. However, multiple subsystems can provide multiple processes to do cleanup and recovery when error conditions occur. This can result in improved performance.

As the number of users on the system increases, you must consider the importance of how subsystems are configured:

vConsider limiting the number of devices that are serviced by a single subsystem. Between 200 and 300 devices for each subsystem are recommended. Use the following recommendations to divide these users:

–The number of users in any given subsystem

–The connectivity used to access the system

–The type of work the users do

–The geographic location of the users

vCreate additional communications and interactive subsystems to split the work into multiple subsystems.

vThe work that is performed in the QCMN subsystem is for connecting and disconnecting from the system. Error recovery considerations are important in the configuration of the communications subsystem.

vTo prevent a subsystem from ever allocating a device, ensure that there are no workstation or type entries for the devices that you do what allocated by that subsystem.

vOnly use the AT(*ENTER) option if you must allow jobs to transfer into that subsystem.

vFor each subsystem you have defined, you need to identify which users will run in which subsystems. Use the Add Work Station Entry (ADDWSE) command and the Remove Work Station Entry (RMVWSE) command. You can set up work stations entries that identify which devices that subsystem should allocate, as well as which devices a subsystem should not allocate.

Note: You can use the ADDWSE commands while the subsystem is active. However, subsystems do not reallocate device locks dynamically. Eventually, it may be necessary to end and restart the subsystems to have the device locks allocated to the desired subsystem.

To specify the devices a communications subsystem should allocate:

ADDCMNE SBSD(libname/sbsname) DEV(devname*) MODE(modename)

To specify the devices a communications subsystem should not allocate:

ADDCMNE SBSD(libname/sbsname) DEV(devname*) MODE(modename) MAXACT(0)

Note: Database and file servers run only in QSERVER. Do not attempt to allocate sessions running over the QSERVER mode description. You can do this by adding the following communication entry to your subsystem:

ADDCMNE (SBSD(libname/sbsname) DEV(devname*) MODE(QSERVER) MAXACT(0)

See the following example for a way of configuring your communications subsystem.

Chapter 3. Optimizing communications performance 11