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

6947ch03.fm

possible to see any places where a control unit, or group of control units, have single points of failure (SPOF); in this case, books and MBAs are of interest.

￿For the next step, use the CFReport for FC2400 along with the same IOCP statements and repeat the availability option in the CMT. This will potentially show a different set of SPOFs.

By comparing the two reports you can determine if FC2400 is the right choice and what, if any, other configuration changes will need to be made in conjunction with the install of FC2400.

I/O port balancing across MBAs and books

At I/O definition time, the customer is able to select I/O ports for different paths of a multi-path control unit that come from different I/O cards; different I/O domains (so, different eSTI-M cards and different STI links); different I/O cages; and different MBAs from different books. This improves I/O throughput and system availability by avoiding single point of failure paths.

Figure 3-7 on page 83 shows a simplified example of multi-path device connectivity.

 

 

2084-D32 CEC Cage

 

 

 

Book 3

Book 0

Book 1

Book 2

MBAMBAMBA MBAMBAMBA MBAMBAMBA MBAMBAMBA

0

1

2

0

1

2

0

1

2

0

1

2

STIs

 

 

 

 

 

 

 

 

 

 

 

STI Links

I/O Cage 1

I/O Cage 2

Book 2

Book 3

Book 0

Book 1

Figure 3-7 Balancing multi-path device connectivity example

Of course, this example assumes that there are enough I/O cards available for such connectivity distribution, and this may not be true for all channel types on a given real configuration. However, the overall goal is to avoid, as much as possible, connectivity single points of failures.

Chapter 3. I/O system structure

83

Page 96 Page 98
Page 97
Image 97
IBM 990 manual Port balancing across MBAs and books, STIs
Page 96 Page 98

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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