6947ch08.fm

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

At this point, even with no partition configuration changes, LP2 and LP3 (shared) partitions may experience performance improvements. As there is now more available capacity (physical processors) to be used by all logical shared CPs, the “logical-to-physical processors ratio” is reduced. In this example, before the upgrade, there were twelve shared logical CPs (six for LP2 and six for LP3) to be dispatched into six physical CPs. If all twelve logical CPs have tasks to run, six of them have to wait. After the physical upgrade, up to seven shared logical CPs can run at the same time.

Now let’s consider the logical upgrades, assuming that all operating systems running in these partitions have the capability of configuring processors online. Partition LP1, which has two reserved CPs defined, can configure up to two more CPs online. In this example, LP1 is configuring one more CP online, remaining with one reserved CP for a future image upgrade. LP1 now has four dedicated CPs, enabled by doing a nondisruptive upgrade.

From the eleven physical CPs available, seven CPs are left to be shared by LP2 and LP3 shared logical CPs.

￿LP2 has six logical CPs and two reserved CPs defined, but only one more can be configured online, as the current configuration has only seven CPs to be shared. After the LP2 logical upgrade, one reserved CP remains offline.

￿LP3 has the same configuration as LP2, and in this example it is not being changed. However, it could have one more reserved CP configured online.

￿LP1 and LP2 remain with one reserved CP each, but they cannot be configured online in the current configuration. However, if LP1 configures one dedicated CP offline, then LP2 can activate its last reserved CP.

Shared partitions and zAAP upgrade

Figure 8-13 on page 213 is an example of a nondisruptive upgrade, adding three zSeries Application Assist Processors (zAAPs) to a 2084-B16, software model 309 server.

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IBM 990 manual Shared partitions and zAAP upgrade
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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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