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

6947ch07.fm

Dynamic ICF expansion can also be configured using dedicated ICF PUs and shared CPs from the z/OS image. The z/OS image must have all CPs defined as shared and the Dynamic

CF Dispatch function must be activated. Dynamic ICF Expansion is available on z990 models that have at least one ICF.

Dynamic ICF Expansion requires that Dynamic CF Dispatching be activated (DYNDISP ON).

Test Sysplex

 

ICF

 

CP

z/OS

z/OS

CF

CF

Test

Prod

 

 

z/OS

z/OS

CF

Test

Prod

 

z990

Partition

Image Profile

Shared Pool of ICF PUs

Dedicated ICFs used for most of the CF requests

Shared ICFs used when requests rates to CF become excessive

Shared ICFs used for take over or spikes (such as alternate CF removed for maintenance or outage occurs)

Function

HMC

Setup

DYNDISP ON (CFCC cmd)

IMAGE Profile setup

Figure 7-6 z990 CF options - Dynamic ICF Expansion

7.3 System-managed CF structure duplexing

System-managed Coupling Facility structure duplexing provides a general purpose, hardware-assisted, easy-to-exploit mechanism for duplexing CF structure data. This provides a robust recovery mechanism for failures, such as loss of a single structure or Coupling Facility, or loss of connectivity to a single Coupling Facility, through rapid failover to the other structure instance of the duplex pair.

7.3.1 Benefits

Benefits of system-managed CF structure duplexing include:

￿Availability

Faster recovery of structures is provided by having the data already in the second Coupling Facility when a failure occurs. Furthermore, if a potential IBM, vendor, or customer Coupling Facility exploitation were being prevented, due to the effort required, from providing alternative recovery mechanisms such as structure rebuild, log recovery, and so forth, system-managed duplexing could provide the necessary recovery solution.

￿Manageability and usability

These benefits are achieved by a consistent procedure to set up and manage structure recovery across multiple exploiters.

￿Cost benefits

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IBM 990 manual System-managed CF structure duplexing, Benefits
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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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