gtps4m0e | System Generation |
HPO contains 2 components: the multiple database function (MDBF) and the loosely coupled (LC) facility. These may be used separately or in combination.
When generating either of these components, you must choose the options needed for the system ahead of time. In either case, the generation procedure involves the use of new macros plus new keywords on base generation macros. MDBF systems require a generation of each subsystem in addition to generating the base system. For LC systems, only one base generation is performed, regardless of the number of processors in the complex.
The multiple database function (MDBF) provides two basic options, but from a generation point of view there are three user choices:
The number of subsystems and subsystem users must be defined before generation. It is recommended that additional subsystems and subsystem users are generated for future expansion. This avoids the need to regenerate the system at a later date. The basic subsystem must be generated first.
A major consideration to keep in mind is that any support required by a particular subsystem must be provided for by the BSS. In addition, any change to a hardware configuration, for example additional DASD devices, will result in a regeneration of all subsystems in addition to the BSS because these devices are defined in the generation of each subsystem. On the other hand, many software support options may be unique to a subsystem and should only be defined for the subsystem that requires them.
TPF provides a number of system generation options for MDBF, along with 2 different versions of the cross subsystem access services CSECT, CCCSAS (one for use with and one for use without MDBF). In a non-MDBF system, the MDBF support code is bypassed, reducing work load and allowing ECB-controlled programs to be identical at the source level.
For loosely coupled complexes, it is important to understand how hardware and some software is to be treated. All hardware and some software can be grouped into one of three categories:
All DASDs are shared with access to data records serialized by the use of an external locking facility (XLF) such as the limited lock facility (LLF) or the concurrency filter lock facility (CFLF) on DASD control units (CUs), or a coupling facility (CF). Any processor in the loosely coupled complex can access and update file resident records. Contention is resolved through a combination of system software and the locking hardware. Processor unique hardware or software is under the exclusive control of a single processor in the loosely coupled complex. For example, unit record devices are handled as processor unique. Software utilities can be made processor unique through the processor resource ownership table (PROT). Switchable resources are addressable by all of the processors but, in fact, are only used by one processor at a time, often with software-enforced controls. Tape devices are an example of a switchable resource. A loosely coupled user should pay close attention during generation to the category to which a resource belongs.
For generation purposes each of the processors in a loosely coupled complex is generated from a single image (for example, a single SIP input deck). There are very few cases (keywords) where the use of this facility must be uniquely treated but the number of physical processors and the hardware configuration must be known before system generation.
The major differences in generating a non-loosely coupled complex are in defining the hardware and in assigning hardware addresses. Shared and switchable resources are usually assigned the same physical addresses in each loosely coupled processor, and this is done as if there is only one processor. Processor unique resources are assigned different addresses, but again, as if there is only one physical processor. In some cases (for example, unit record devices) the different physical devices can in fact have the same addresses and those addresses are only specified once. In other cases, the physical addresses must be different. Each device type has its own rules that must be followed.
Unique to a loosely coupled generation is the need to define the processor resource ownership table (see data macro PR1OT). This is done using the SIP macro, UTPROT. Another SIP macro, GLSYNC, is used to define the records and fields that are located in the global area, which must be synchronized between all I-streams in the complex. Use of the globals in this environment is more fully described in TPF System Installation Support Reference.
Another major generation consideration of a loosely coupled complex is the requirement for an EP processor if there is a need to support 3705 EP or 3270 locally attached devices. It should also be noted that a number of software functions that are only associated with 3705 EP (for example, message switching) are performed only by the EP processor. The first processor in the loosely coupled complex is automatically designated the EP processor. See the SYSID parameter of the CONFIG macro.
Users are cautioned to consider all aspects of a loosely coupled complex. For example, an NEF-supported ALC terminal can be considered to be shared by all loosely coupled processors because there is a path to it from all processors, but the user's NCP generation may direct that terminal to send all input messages to only one of the processors.
Users must generate the system to accommodate expansion and collapse of the loosely coupled complex. In addition, consideration must be given to the necessity to switch over any one of the processors in the loosely coupled complex to another physical processor. It is recommended that the system be initially generated with the maximum number of processors that will be required throughout system life rather than forcing a complete regeneration to add additional processors to the complex in the future. Switchover may be accomplished by treating the fallback processor as an additional processor in the complex (for example, defining 3 processors versus just 2 that are really needed, but never actually using 3); or by a hardware configuration where a backup processor can simply replace any existing processor in the complex. The key is to lay out the hardware in a manner that best suits user requirements before attempting to generate a system to support the required hardware configuration.