6947ch02.fm

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

￿z/VM can be configured to use 64-bit addressing and operate in the z/Architecture mode, or to use 31-bit addressing and operate in the ESA/390 architecture mode.

2.2.9Reserved storage

Reserved storage can optionally be defined to a logical partition allowing a non-disruptive image memory upgrade for this partition. Reserved storage can be defined to both central and expanded storage, and to any image mode except the Coupling Facility mode.

A logical partition must define an amount of central storage and optionally (if not a Coupling Facility image) an amount of expanded storage. Both central and expanded storages can have two storage sizes defined: an initial value, and a reserved value:

￿The initial value is the storage size allocated to the partition when it is activated.

￿The reserved value is an additional storage capacity beyond its initial storage size that a logical partition can acquire dynamically. The reserved storage sizes defined to a logical partition do not have to be available when the partition is activated. They are just pre-defined storage sizes to allow a storage increase from the logical partition point of view.

Without the reserved storage definition, a logical partition storage upgrade is disruptive, requiring:

￿Partition deactivation

￿An initial storage size definition change

￿Partition activation

The additional storage capacity to a logical partition upgrade can come from:

￿Any unused available storage

￿Another partition which has released some storage

￿A concurrent CPC memory upgrade

A concurrent logical partition storage upgrade uses Dynamic Storage Reconfiguration (DSR) and the operating system must use the Reconfigurable Storage Units (RSUs) definition to be able to add or remove storage units. Currently, only z/OS and OS/390 operating systems have this support.

2.2.10 LPAR storage granularity

Storage granularity for Central Storage and Expanded Storage in LPAR mode varies as a function of the total installed storage, as shown in Table 2-10.

This information is required for Logical Partition Image setup and for z/OS and OS/390 Reconfigurable Storage Units definition.

Table 2-10 LPAR storage granularity

Total installed memory

Partition storage granularity (CS and ES)

 

 

installed memory <= 32 GB

64 MB

 

 

32 GB < installed memory <= 64 GB

128 MB

 

 

64 GB < installed memory <= 128 GB

256 MB

 

 

128 GB < installed memory <= 256 GB

512 MB

 

 

70IBM eServer zSeries 990 Technical Guide

Page 83 Page 85
Page 84
Image 84
IBM 990 manual Reserved storage, Lpar storage granularity
Page 83 Page 85

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