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

6947ch04.fm

Driver

 

 

 

D32

 

 

C24

 

B16

 

 

A08

 

 

 

 

 

1-8 PUs

0-8 PUs

0-8 PUs

0-8 PUs

 

 

 

 

16 - 64 GB

0 - 64 GB

0 - 64 GB

0 - 64 GB

 

 

 

 

Logical Partitions

LCSS 0

LCSS 1

LCSS 2

LCSS 3

up to 256

up to 256

up to 256

up to 256

CHPIDs

CHPIDs

CHPIDs

CHPIDs

HSA

IOCDS

1-12 STIs 0-12 STIs 0-12 STIs 0-12 STIs

Physical Channels (PCHIDs)

Single Driver/LIC (CEC-wide)

Up to 4 books per CEC

Active Processing Units (min 1, max 32)

Memory (min 16 GB, max 256 GB)

Up to 15 Logical Partitions per LCSS Up to 30 Logical Partitions per CEC

Up to 4 Logical Channel Subsystems

Single HSA with one active IOCDS that provides a single system image for I/O

Self-Timed Interconnect cables I/O Cage with features

Figure 4-1 Logical view of IBM 2084 models, LCSSs, IOCDS and HSA1

It is important to note that an IBM 2084 is one processor with logical extensions. All Channel Subsystem Images (CSS Image or LCSS) are defined within a single IOCDS. The IOCDS is loaded and initialized into the Hardware System Area at Power-on Reset.

There is no HSA expansion support for dynamic I/O on the z990 Support Element. The HSA allocation is controlled by the “maximum number of devices” field on the HCD Channel Subsystem List panel. This value can only be changed by a Power-on Reset. Figure 4-1shows a logical view of the relationships. It must be noted that each LCSS supports up to 15 logical partitions but system wide a total of up to 30 logical partitions are supported.

Note: HSA is always allocated in the physical memory of Book 0.

The channel definitions of an LCSS are not bound to a single book. An LCSS may define resources that are physically connected to all STIs of all books in any multi-book IBM 2084 model.

Multiple Image Facility (MIF)

Multiple Image Facility (MIF) enables resource sharing across logical partitions within a single LCSS or across the LCSSs. When a channel resource is shared across logical partitions in multiple LCSS, this is known as “spanning”; refer to 4.1.3, “Channel spanning” on page 114 for more information about spanning.

With the introduction multiple LCSSs, the IOCDS logical partition MIF Image id is no longer unique within the z990 server. Therefore, the logical partition identifier value has been changed to provide a unique value for each logical partition within the same z990 server. The following terminology applies:

Logical partition number

The logical partition number cannot be specified by the user; actually, it is not even visible to the user. On the z990, it is assigned at Power-on Reset by PR/SM and is based on the total

1Although each LCSS supports up to 15 logical partitions it should be noted that system wide up to 30 logical partitions are supported.

Chapter 4. Channel Subsystem 111

Page 124 Page 126
Page 125
Image 125
IBM 990 manual Multiple Image Facility MIF, Logical partition number
Page 124 Page 126

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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