6947ch08.fm

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

￿Changing the number of logical partitions defined to a z990 server.

The only way to add or delete a logical partition is by a POR using a new IOCDS including or excluding the new partition.

￿Changing the number of LCSS on a server.

￿Changing the number of subchannels supported on a LCSS.

￿Logical partition processor upgrades when reserved processors were not previously defined are disruptive to image upgrades.

￿Memory capacity upgrades are disruptive when memory cards replacement is required.

￿Logical partition memory upgrades when reserved storage was not previously defined are disruptive to image upgrades.

￿Installation of I/O cages is disruptive.

￿An I/O upgrade when the operating system cannot use the Dynamic I/O configuration function.

–Linux and CFCC do not support Dynamic I/O configuration.

–If there is no space available in the reserved HSA for the required I/O expansion.

￿An STI rebalancing, when the STI Rebalance feature (Feature Code 2400) is ordered at the server’s upgrade configuration time.

￿Adding a PCIXCC or a PCICA coprocessor to a logical partition, if not predefined with the appropriate PCI cryptographic processor number selected in the PCI Cryptographic Candidate List of the logical partition’s image profile.

Recommendations to avoid disruptive upgrades

Based on the previous list of reasons for disruptive upgrades, here are some recommendations to avoid or at least minimize these situations, increasing the possibilities for nondisruptive upgrades:

￿Define spare or reserved logical partitions.

A z990 server can have up to 30 logical partitions defined. It is possible to define more partitions than you need in the initial configuration, just by:

–including more partition names in the IOCP statement RESOURCE. The spare partitions do not need to be activated, so any valid partition configuration can be used during their definitions. The initial definitions (LPAR mode, processors, and so on) can be changed later to match the image type requirements.

The only resource that spare partitions will use is subchannels, so careful planning must be done here, keeping in mind that z990s can have up to 1890 K subchannels (63 K per logical partition * 30 partitions) total in HSA.

–defining reserved logical partitions, if you are running z/OS V1.6 or higher. The dynamic logical partition name definition allows reserved partition ‘slots’ to be created in an IOCDS in the form of extra logical channel subsystem, Multiple Image Facility (MIF) image pairs. These extra logical channel subsystem MIF image ID pairs (CSSID/MIFID) can be later assigned a logical partition name for use (or later removed) via dynamic I/O commands using the Hardware Configuration Definition (HCD), concurrently. A reserved partition is defined with the partition name placeholder ‘ * ’, and cannot be assigned to access or candidate list of channel paths or devices. The IOCDS still must have the extra I/O slots defined in advance, since structures are built in the Hardware System Area (HSA).

￿Define an appropriate number of Logical Channel Subsystems (LCSSs).

216IBM eServer zSeries 990 Technical Guide

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IBM 990 manual Recommendations to avoid disruptive upgrades
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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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