Addcmne SBSDlibname/sbsname DEVdevname* MODEmodename

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

AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.