6947ch07.fm

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

7.2.4 Coupling Facility link connectivity

The type of CF links you can use to connect a CF to an operating system logical partition is important because of the impact of the link performance on response times and coupling overheads. For configurations covering large distances, the time spent on the link can be the largest part of the response time (mainly if the CF is defined on a z990 server).

The types of links that are available to connect an operating system logical partition to a Coupling Facility are:

￿IC - Licensed Internal Code defined links to connect a CF to a z/OS logical partition in the same z990 processor. IC links require two CHPIDs to be defined and can only be defined in Peer mode. The link bandwidth is greater than 2 GB/sec. A maximum of 32 IC links can be defined per z990.

￿ICB-4 - Copper links available to connect z990 to z990, or z890 processors; the maximum distance between the two processors is 7 meters (maximum cable length is 10 meters). The link bandwidth is 2GB/sec. ICB-4 links can only be defined in Peer mode. Maximum number of ICB-4 links is 16 per z990.

￿ICB-3 - Copper links available to connect a z990 to z990, z890, z900, or z800 processors; the maximum distance between the two processors is 7 meters (maximum cable length is 10 meters). The link bandwidth is 1 GB/sec. ICB3 links can only be defined in Peer mode. Maximum number of ICB-3 links is 16 per z990.

￿ICB-2 - Copper links available to connect a z990 to a 9672 G5/G6 processors (you cannot use ICB-2 to connect a z990 to a z900 or to another z990); the maximum distance between the two processors is 7 meters (maximum cable length is 10 meters). The link bandwidth is 333 MB/sec. Maximum number of ICB-2 links is 8 per z990.

￿ISC-3 - The z990 ISC-3 feature is compatible with Coupling Links/ISCs (referred to as a Hiperlink on G5/G6 Servers) on S/390 generation 5 and generation 6 servers as well as zSeries 890, zSeries 900 and zSeries 800. Each port is capable of 1 Gbps or 2 Gbps depending upon the mode of operation selected in the Hardware Configuration Definition (HCD) tool or IOCP. Ports are ordered in increments of one. The maximum number of ISC-3 links per z990 is 48 in peer mode, and 32 ISC-3 links in compatibility mode.

–There are fiber links available to connect z990 to z990, z890, z900 or z800 processors; the maximum distance is 10 km, 20 km with RPQ 8P2197 and 40 km with Dense Wave Division Multiplexing (DWDM). ISC-3s operate in single mode only and link bandwidth is 200MB/sec for distances up to 10 km, and 100MB/sec when RPQ 8P2197 is installed. ISC-3 links should be defined in peer mode. The peer mode is used between zSeries servers only.

–There are fiber links available to connect z990 to G5 and G6 servers. The z990 ISC-3 feature is compatible with Coupling Links/ISCs (referred to as a Hiperlink) on G5/G6 servers. Compatibility mode is used between the z990 and G5/G6 servers. The port is defined as a sender/receiver (CFS/CFR) channel and the link is capable of 1 Gbps.

Table 7-2 z990 Coupling Link maximums

Link Type

z990 Max

 

 

IC

32

 

 

ISC-3

48a

ICB-2

8

 

 

ICB-3

16

 

 

ICB-4

16

 

 

162IBM eServer zSeries 990 Technical Guide

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IBM manual Coupling Facility link connectivity, Link Type Z990 Max
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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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