The 1990s

The ES/9000 was announced in September 1990. The ES/9000 family included three design points: a rack-mounted ES/9221, an air-cooled ES/9121, and a water-cooled ES/9021. ES/9000 processors implemented Enterprise Systems Architecture (ESA), an extension of 370-XA.

An IBM 3390 DASD subsystem

To the delight of VSE customers, VSE experienced a major revitalization in the 1990s. VSE/SP became VSE/ESA Version 1. VSE/ESA V1 kept the best parts of VSE/SP and focused on quality, capacity, and MVS ‘affinity’.

For increased capacity, VSE/ESA V1 first implemented 31-bit for real memory, then added 31-bit virtual addressing. VSE/ESA V1 offered dynamic partitions (limited by available tasks). VSE/ESA V1 offered virtual storage constraint relief (VSCR) by moving ACF/VTAM and POWER out of shared partitions. It introduced dynamic channels (the XA channel subsystem), ESCON channels, and up to 1024 devices for added I/O bandwidth. In later releases, VSE/ESA V1 added support for ESA data spaces and Virtual Disk in storage. VSE/ESA V1 exploited ESA access registers. New versions of CICS/VSE, ACF/VTAM, and VS COBOL II were added for greater MVS affinity.

The lab began to work closely with ISVs. Prior to VSE/ESA, ISVs had to wait like everyone else until General Availability. Only then could they adapt their own products to the latest VSE release. The result was that few customers could exploit the latest release of VSE until the ISVs changed their products. The delay served no one’s interest. The practice is now to involve ISVs as soon as possible. ISVs have early access to VSE plans, design specifications, and code.

A rack mounted, air-cooled ES/9221 with rack mounted disk and tape.

In 1993, an imaginary VSE/ESA V1.3 customer might have an IBM ES/9221-150 with 128MB of main memory, 8 IBM 9336 (470 MB per actuator in early models) disk drives, and an IBM 3490 tape unit.

VSE/ESA V1 also established itself in distributed processing. Distributed capabilities, many of which were first introduced in VSE/SP V4, allowed VSE systems to be managed from a central location. During the 1990s, several large IBM customers were able to manage enormous numbers of remote IBM MicroChannel/370 (9371) systems. However, this proved to be a temporary ‘niche’. For some customers, consolidated, centralized solutions replaced distributed ones. For others, newer network technology replaced the comparatively rigid, centrally managed approach.

In 1994, after many ‘experts’ had declared ‘big iron’ dead, IBM boldly reinvented the mainframe. At the time, the fastest systems used bipolar semiconductor technology. Unfortunately, bipolar has the disadvantage of being expensive and using lots of power (more heat). Large mainframe systems based on bipolar technology often required large water-cooling units.

The alternative technology, CMOS, was comparatively slow (at the time), but used less electricity (less heat). In addition, since it was more widely used, CMOS components were cheaper to design and build. IBM was confident that CMOS technology would advance quickly and eventually surpass bipolar. The decision turned out to be the right one. In 2005 the most powerful zSeries servers (the z990) are based on CMOS.

An IBM 9672 G1 server

The IBM S/390 Parallel Enterprise Server G1 was introduced in 1994. More powerful S/390 CMOS models followed quickly. S/390 Servers also featured an Open Systems Adapter (OSA) for fast, economical network connectivity.

To exploit IBM’s CMOS servers, VSE/ESA V2 replaced V1 in 1994. VSE/ESA V2 introduced the Turbo dispatcher. For the first time VSE supported n-way servers. VSE/ESA V2 also introduced Language Environment technology and newer levels of COBOL, PL/1, and C for increased MVS affinity. ACF/VTAM V4.2 was added as well.

IBM also used S/390 technology to create systems designed for smaller customers. For example, in 1996 the IBM S/390 Multiprise 2000 offered up to 5 processors (CPs), up to 288 GB internal disk (using 3380/3390 ECKD format), and OSA adapters. The Multiprise 2000 was a very good match for many VSE customers.

An IBM Multiprise 2000 with the signature yellow 'speed bump'.

VSE/ESA V2.2 shipped in late 1996. It was the first VSE to be ‘Year 2000’ ready.

The Year 2000 ‘problem’ had its origins in the early days of S/360 when memory was a precious resource and 2000 seemed far in the future. Widespread practice was to store and process only the last two digits of the year. For example, "1972" was stored as "72", "1996" was "96", and "2000" was "00". As 2000 approached, systems and business applications were exposed. For example, subtracting 72 from 96, the correct answer is 24. However, subtracting 72 from 00, the answer is negative 72 (mathematically OK, but incorrect for its intended use). This simple, seemingly trivial mistake had the potential to seriously disrupt both the financial integrity and the operational effectiveness of many companies.

An IBM 3490E Magnetic Tape Subsystem

During this period, TCP/IP became the de facto standard for networking. In 1997, VSE/ESA V2.3 introduced a native TCP/IP (licensed from CSI International) implementation.

In 1998, an imaginary VSE/ESA V2.3 customer might have an IBM Multiprise 2000 with 2 CPs, 1 GB of main memory, up to 288 GB of internal disk drives (3380 or 3390 format), and an IBM 3490E tape unit.

VSE/ESA V2.4 launched CICS Transaction Server for VSE/ESA (although CICS/VSE continued to ship along with CICS TS VSE/ESA for compatibility reasons). Because CICS TS VSE/ESA was built on the same code base as the equivalent MVS product, it represented a major expansion of MVS affinity.

Many VSE customers spent the last years of the 1990s enabling their systems and applications to be ‘Year 2000 ready’.



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