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

6947ch07.fm

System automation - I/O operations

When using system automation, take care when using PROHIBIT or BLOCK on a port that is participating in Dynamic Channel Path Management.

When blocking a managed channel port, configuring the CHPID OFFLINE to all members of the LPAR Cluster is all that is required. Dynamic Channel Path Management will ensure that if the CHPID is configured to managed subsystems, then the CHPID will be deconfigured from all subsystems to which it is currently configured.

When blocking a port connected to a managed subsystem, the port must first be disabled for Dynamic Channel Path Management usage. This is done using the VARY SWITCH command to take the port OFFLINE to Dynamic Channel Path Management. This command should be issued on all partitions that are running DCM. Disabling the port for Dynamic Channel Path Management usage will deconfigure all managed channels which are connected to the subsystem through that port. Once the port is disabled to Dynamic Channel Path Management, it can then be blocked.

When prohibiting a set of ports, if any of the ports are connected to managed subsystems, then the PROHIBIT operation must be preceded by the VARY SWITCH command(s) to disable the managed subsystem ports to Dynamic Channel Path Management. As in the blocking case, this will cause any managed channels currently connected to the subsystem port(s) to be deconfigured. Once the subsystem ports are disabled to Dynamic Channel Path Management, the PROHIBIT function can be invoked. This must then be followed by the VARY SWITCH command(s) to re-enable the prohibited subsystem ports to Dynamic Channel Path Management.

When ports are unprohibited or unblocked, these operations need to be followed, as necessary, by VARY SWITCH commands to bring ports ONLINE to Dynamic Channel Path Management.

7.5.6 References

For more detailed information on Intelligent Resource Director, see z/OS MVS Planning Workload Management, SA22-7602, and the IBM Redbook z/OS Intelligent Resource

Director, SG24-5952.

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IBM 990 manual References, System automation I/O operations
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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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