6947ch04.fm

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

In each LCSS, the CHPIDs are shared across all logical partitions. The CHPIDs in each LCSS can be mapped to their designated PCHIDs using the CHPID Mapping Tool (CMT), or manually using HCD or IOCP. The output of the CMT is used as input to HCD or the IOCP to establish the CHPID to PCHID assignments. See 4.2.1, “z990 configuration management” on page 116 for further details on the CMT.

LPAR name

LP1

LP2

 

LP3

LP14

LP15

 

LP16

LPAR ID

00

0B

 

0C

11

13

 

1A

MIF ID

1

3

 

5

2

3

 

5

LCSS

 

LCSS 0

 

 

LCSS 1

 

CHPID

80

81

90

91

80

81

90

91

PCHID

140

150

1E0

1F0

141

151

1E1

1F1

 

Directors

01

 

 

 

02

 

 

 

Control Units

 

DASD

DASD

 

 

 

and Devices

 

 

 

 

 

LCUs

LCUs

 

 

 

Figure 4-3 z990 LCSS connectivity

 

 

 

 

 

4.1.3 Channel spanning

Channel spanning extends the MIF concept of sharing channels across logical partitions to sharing channels across Logical partitions and Logical Channel Subsystems.

Spanning is the ability for the channel to be configured to multiple Logical Channel Subsystems. When defined that way, the channels can be transparently shared by any or all of the configured logical partitions, regardless of the Logical Channel Subsystem to which the logical partition is configured.

A channel is considered a spanned channel if the same CHPID number in different LCSSs is assigned to the same PCHID in IOCP, or is defined as “spanned” in HCD.

In the case of internal channels (for example, IC links and HiperSockets), the same applies but there is no PCHID association. They are defined with the same CHPID number in multiple LCSSs.

CHPIDs that span LCSSs reduce the total number of channels available on the z990. The total is reduced since no LCSS can have more than 256 CHPIDs. For a z990 with two LCSS, a total of 512 CHPIDs are supported. If all CHPIDs are spanned across the two LCSSs, then only 256 channels can be supported. For a z990 with four LCSSs, a total of 1024 CHPIDs are supported. If all CHPIDs are spanned across the four LCSSs, then only 256 channels can be supported.

114IBM eServer zSeries 990 Technical Guide

Page 127 Page 129
Page 128
Image 128
IBM manual Channel spanning, Z990 Lcss connectivity
Page 127 Page 129

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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