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

6947ch02.fm

Note: The z990 (and the z890) are the last zSeries servers offering Token Ring adapters on the Hardware Management Consoles and Support Elements.Timely planning is advised in preparation of migration to the Ethernet environment.

Note: Hardware Management Consoles are to become closed platforms with the next zSeries server and will only support the HMC application. Other applications, such as for the IBM ESCON Director and the IBM Sysplex Timer will no longer be supported from the HMC. Timely planning for needed console equipment for Directors and Timers is recommended. When available these HMCs can only communicate with Generation 5 servers and later (Multiprise 3000, G5, G6, z800, z900, z890, z990) and TCP/IP will be the only communication protocol supported.

For further information on the Hardware Management Console and SEs, refer to Appendix A, “Hardware Management Console (HMC)” on page 233.

Dual External Time Reference

The z990 implements a dual External Time Reference (ETR). The optional ETR cards provide the interface to the IBM Sysplex Timers, which are used for timing synchronization between systems in a Sysplex environment.

If z990 models have coupling links, then two ETR cards with dual paths to each book are installed, allowing continued operation even if a single ETR card fails. This redundant design also allows concurrent maintenance.

2.2.8 Storage operations

In z990 servers, memory can be assigned as a combination of central storage and expanded storage, supporting up to 30 logical partitions.

Before you activate a logical partition, central storage (and optional expanded storage) must be defined to the logical partition. All installed storage can be configured as central storage. Each individual logical partition can be defined with a maximum of 128 GB of central storage.

Central storage can be dynamically assigned to expanded storage and back to central storage as needed, without a Power-on Reset (POR); refer to “LPAR single storage pool” on page 55 for further details.

Memory cannot be shared between system images. You can dynamically reallocate storage resources for z/Architecture and ESA/390 Architecture mode logical partitions running operating systems that support Dynamic Storage Reconfiguration (DSR); refer to “LPAR Dynamic Storage Reconfiguration (DSR)” on page 71 for further details.

Operating systems running under z/VM can exploit the z/VM capability of implementing virtual memory to guest virtual machines. The z/VM dedicated real storage can be “shared” between guest operating systems’ memories.

Figure 2-18 on page 68 shows the z990 modes and memory diagram, summarizing all image modes, with their processor types and the Central Storage (CS) and Expanded Storage (ES) definitions allowed for each mode.

Chapter 2. System structure and design 67

Page 80 Page 82
Page 81
Image 81
IBM 990 manual Storage operations, Dual External Time Reference
Page 80 Page 82

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.
Top Page Image Contents