6947ch02.fm

Draft Document for Review April 7, 2004 6:15 pm

PR/SM enables z990 servers to be initialized for logically partitioned operation, supporting up to 30 logical partitions. Each logical partition can run its own operating system image in any image mode, independently from the other logical partitions.

A logical partition can be activated or deactivated at any time, but changing the number of defined logical partitions is disruptive, as it requires a Power-on Reset (POR). Some facilities may not be available to all operating systems, as they may have software corequisites.

Each logical partition has the same resources as a “real” CPC, which are:

￿Processor(s)

Called Logical Processor(s), they can be defined as CPs, IFLs, ICFs, or zAAPs. They can be dedicated to a partition or shared between partitions. When shared, a processor weight

can be defined to provide the required level of processor resources to a logical partition. Also, the capping option can be turned on, which prevents a logical partition from acquiring more than its defined weight, limiting its processor consumption.

For z/OS Workload License Charge (WLC), a logical partition “Defined Capacity” can be set, enabling the soft capping function.

ESA/390 mode logical partitions can have CPs and zAAPs logical processors. Both logical processor types can be defined as either all dedicated or all shared. The zAAP support is planned to be introduced by z/OS 1.6.

Only Coupling Facility (CF) partitions can have both dedicated and shared logical processors defined.

Figure 2-16 shows the logical processor assignment screen of the Customize Image Profile on the Hardware Management Console (HCM), for an ESA/390 mode image. This panel allows the definition of:

–Dedicated or shared logical processors, including CPs and zAAPs (remember that zAAPs initially appear as “Integrated Facility for Applications” on HCM panels).

–The initial weight, optional capping and Workload Manager options for shared CPs (shared zAAPs weight equals to CPs weight, but share calculation is based on the sum of ICFs, IFLs and zAAPs weights).

–The number of initial and optional reserved processors (CPs).

–The optional number of initial and reserved integrated facility for application (zAAPs).

58IBM eServer zSeries 990 Technical Guide

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IBM 990 manual Processors
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990 specifications

The IBM 990 series, often referred to in the context of IBM's pioneering efforts in the realm of mainframe computing, represents a unique chapter in the history of information technology. Introduced in the late 1960s, the IBM 990 series was designed as a powerful tool for enterprise-level data processing and scientific calculations, showcasing the company's commitment to advancing computing capabilities.

One of the main features of the IBM 990 was its architecture, which was built to support a wide range of applications, from business processing to complex scientific computations. The system employed a 32-bit word length, which was advanced for its time, allowing for more flexible and efficient data handling. CPUs in the IBM 990 series supported multiple instructions per cycle, which contributed significantly to the overall efficiency and processing power of the machines.

The technology behind the IBM 990 was also notable for its use of solid-state technology. This provided a shift away from vacuum tube systems that were prevalent in earlier computing systems, enhancing the reliability and longevity of the hardware. The IBM 990 series utilized core memory, which was faster and more reliable than the magnetic drum memory systems that had been standard up to that point.

Another defining characteristic of the IBM 990 was its extensibility. Organizations could configure the machine to suit their specific needs by adding memory, storage, and peripheral devices as required. This modular approach facilitated the growth of systems alongside the technological and operational demands of the business environments they served.

In terms of software, the IBM 990 series was compatible with a variety of operating systems and programming environments, including FORTRAN and COBOL, enabling users to access a broader array of applications. This versatility was a significant advantage, making the IBM 990 an appealing choice for educational institutions, research facilities, and enterprises alike.

Moreover, the IBM 990 was engineered to support multiprocessing, which allowed multiple processes to run simultaneously, further increasing its effectiveness in tackling complex computing tasks.

In summary, the IBM 990 series represents a significant advancement in computing technology during the late 20th century. With a robust architecture, versatile configuration options, and a focus on solid-state technology, the IBM 990 facilitated substantial improvements in data processing capabilities, making it a cornerstone for many businesses and academic institutions of its time. Its impact can still be seen today in the continued evolution of mainframe computing.
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