6947ch02.fm

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

Within the limit of all non-characterized PUs available in the installed configuration, IFLs can be concurrently added to an existing configuration via Capacity Upgrade on Demand (CUoD),

Customer Initiated Upgrade (CIU), On/Off Capacity on Demand (On/Off CoD), but IFLs cannot be assigned via CBU. For more information about CUoD, CIU or On/Off CoD see

Chapter 8, “Capacity upgrades” on page 185. If the installed books have no unassigned PUs left, the assignment of the next IFL may require the installation of an additional book.

Internal Coupling Facilities

An Internal Coupling Facility (ICF) is a PU used to run the IBM Coupling Facility Control Code (CFCC) for Parallel Sysplex environments. Within the capacity of the sum of all unassigned PUs in up to four books, up to 16 ICFs can be characterized, depending on the z990 model. You need at least an IBM 2084 model B16 to assign 16 ICFs. ICFs can be concurrently assigned to an existing configuration via Capacity Upgrade on Demand (CUoD), On/Off Capacity on Demand (On/Off CoD), or Customer Initiated Upgrade (CIU), but ICFs cannot be assigned via CBU.

For more information about CUoD, CIU, or On/Off CoD see Chapter 8, “Capacity upgrades” on page 185. If the installed books have no non-characterized PUs left, the assignment of the next ICF may require the installation of an additional book.

The ICF processors can only be used by Coupling Facility logical partitions. ICF processors can be dedicated to a CF logical partition, or shared by multiple CF logical partitions running in the same z990 server.

All ICF processors within a configuration are grouped into the ICF/IFL/zAAP processor pool. The ICF/IFL/zAAP processor pool appears on the hardware console as ICF processors. The number of ICFs shown is the sum of IFL, ICF, and zAAP processors on the system.

Only Coupling Facility Control Code (CFCC) can run on ICF processors; ICFs do not change the model type of the z990 server. This is important because software product license charges based on the software model number are not affected by the addition of ICFs.

Dynamic ICF Expansion

Dynamic ICF Expansion is a function that allows a CF logical partition running on dedicated ICFs to acquire additional capacity from the LPAR pool of shared CPs or shared ICFs. The trade-off between using ICF features or CPs in the LPAR shared pool is the exemption from software license fees for ICFs. Dynamic ICF Expansion is available on any z990 model that has at least one ICF.

Dynamic ICF Expansion requires that the Dynamic CF Dispatching be turned on (DYNDISP ON). For more information, see “Dynamic CF dispatching and dynamic ICF expansion” on page 166.

Dynamic Coupling Facility Dispatching

The Dynamic Coupling Facility Dispatching function has an enhanced dispatching algorithm that lets you define a backup Coupling Facility in a logical partition on your system. While this logical partition is in backup mode, it uses very little processor resource. When the backup CF becomes active, only the resource necessary to provide coupling is allocated.

The CFCC command DYNDISP controls the Dynamic CF Dispatching (use DYNDISP ON to enable the function). For more information, see “Dynamic CF dispatching and dynamic ICF expansion” on page 166.

48IBM eServer zSeries 990 Technical Guide

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IBM 990 manual Internal Coupling Facilities, Dynamic ICF Expansion, Dynamic Coupling Facility Dispatching
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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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