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

6947ch03.fm

This function does not apply to IPv6 packets. TCP/IP will continue to perform all checksum processing for IPv6 packets. This function also does not apply to ICMP checksum processing. TCP/IP will continue to perform processing for ICMP checksum.

Checksum offload is supported by the OSA-Express GbE features (FC 1364, FC 1365) and the 1000BASE-T Ethernet feature (FC 1366) when operating at 1000 Mbps (1 Gbps). This is applicable to the QDIO mode only (channel type OSD).

z/OS support for Checksum offload is planned to be available in z/OS V1.5.

For Linux for zSeries support, refer to the following Web site for further information:

http://www.ibm.com/developerworks.

z990 adapter interruptions enhancement for QDIO

The z990 servers, Linux for zSeries, and z/VM work together to provide performance improvements by exploiting extensions to the Queued Direct Input/Output (QDIO) architecture. Adapter Interruptions, first added to z/Architecture with HiperSockets, provide an efficient, high-performance technique for I/O interruptions to reduce path lengths and overhead in both the host operating system and the adapter - OSA-Express when using the OSD CHPID type.

In extending the use of adapter interruptions to OSD (QDIO) channels, the programming overhead to process a traditional I/O interruption is reduced. This benefits OSA-Express TCP/IP support in both Linux for zSeries and z/VM.

Adapter interruptions apply to all of the OSA-Express features available on z990, whether offered as a new build or on an upgrade from z900 when in QDIO mode (CHPID type OSD).

HiperSockets function

The HiperSockets function, also known as internal Queued Direct Input/Output (iQDIO) or internal QDIO, is an integrated function of the z990 server which provides users with attachment to up to sixteen high-speed “virtual” Local Area Networks (LANs) with minimal system and network overhead.

HiperSockets eliminates the need to utilize I/O subsystem operations and the need to traverse an external network connection to communicate between logical partitions in the same z990 server. HiperSockets offers significant value in server consolidation connecting many virtual servers, and can be used instead of certain XCF link configurations in a Parallel Sysplex.

HiperSockets are customizable to accommodate varying traffic sizes. Since HiperSockets does not use an external network, it can free up system and network resources, eliminating attachment costs while improving availability and performance.

3.4.5 Coupling Facility links

Following are Coupling Facility links connectivity options in the Parallel Sysplex environment. For more information about Parallel Sysplex connectivity, see “Coupling Facility link connectivity” on page 162.

z990 coupling link features

z990 supports the following coupling link features:

￿Inter-System Channel-3, ISC-3 (Peer and Compatibility modes), feature codes 0217, 0218, and 0219

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IBM manual Coupling Facility links, Z990 adapter interruptions enhancement for Qdio, HiperSockets function
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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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