When IBM introduced the System/390 line of servers in 1990, some industry experts predicted a brief lifespan for the mainframe. In the March 1991 issue of the trade magazine InfoWorld, editor Stewart Alsop prophesied, “I predict that the last mainframe will be unplugged on March 15, 1996.” Such prognostications about the death of so-called big iron proved to be premature.
The predictions were founded on what felt like a turning point in the marketplace. In 1984, sales of desktop computers exceeded mainframes for the first time. This seemed to suggest that giant servers would increasingly cede the market to smaller, decentralized computers. Then 1989 happened.
That’s when Tim Berners-Lee, a British scientist at CERN, invented the World Wide Web, which would quickly have far-reaching commercial applications for computing. Less than two years after System/390 was introduced, the first widely used internet service provider, America Online, issued its initial public offering, and the phrase “surfing the internet” became part of the lexicon.
The rapid rise of the internet made powerful and reliable mainframe computers more important than ever. Businesses quickly set up websites to offer a host of online products and services. They needed fast and reliable mainframes to handle the surge of traffic.
System/390 was ideally suited to meet those emerging needs. It was a secure and highly reliable system, with twice the processing speed of IBM’s previous offering. It was also compact. In contrast to earlier mainframes, which took up an entire room, System/390 machines were no bigger than a home entertainment center and consumed significantly less power.
System/390 wasn’t a single unit but rather a family of 18 processor models, from midrange computers for office environments to the most powerful computers IBM had ever offered. It gave users a common platform across all models, making it easy for customers to upgrade along clearly defined paths. The operating system, OS/390, was introduced in late 1995 to provide a fully functional multiple virtual storage package. OS/390 improved the realizability, availability and serviceability for the operating system and reduced the time required for customers to test and deploy the operating system in their environments.
The range of growth options — from the smallest rack-mounted office system to the high-performance, six-way multiprocessor — helped to ensure smooth transitions for customers as their computing requirements increased. Programs and applications based on IBM’s previous System/370 architecture ran on System/390 with little or no modification, protecting customers’ existing investments in software as they moved upward in the new, higher-function family.
System/390 featured enhanced capabilities to manage information systems, increased processing power and improved network management, all important advances to handle the mushrooming processing demands of the internet age.
As the internet became commonplace in modern life, businesses quickly realized they were all, in effect, open 24/7. They needed mainframes that could minimize, if not eliminate, downtime.
System/390 processors made it possible to concurrently repair an offline central processor and keep central processors functioning. System/390 also featured an enhanced power system to provide continued operation for power-supply failures and enabled reconfiguration of input/output equipment without impacting the system.
Other new technologies in System/390 included high-speed fiber-optic channels that enabled customers for the first time to locate traditional “computer room” equipment in entirely different buildings — anywhere within roughly five miles of the central processor’s location.
Internet traffic soared throughout the 1990s, placing ever greater demands on mainframes to handle the volume. By 1997, there were more than 1 million websites worldwide; three years later, that number had surpassed 17 million. To keep up, IBM introduced a series of upgrades to System/390.
In 1994, IBM debuted System/390 Parallel Servers, a major improvement to System/390. It offered users a low-risk upgrade that reduced energy cost by 40 percent while increasing performance more than threefold. In 1997, System/390 servers debuted with advanced microprocessors that were both more powerful and less costly to maintain. A year later, the S/390 G5 Parallel Enterprise Server 10-way Turbo model, which was capable of processing 1,000 MIPS (million instructions per second), became the world’s most powerful mainframe. By the late 1990s, nearly two-thirds of the world’s data resided on IBM servers, mostly S/390 mainframes.
In 2000, the processing demands of the internet became too much for even System/390 to handle. It was replaced by the eServer zSeries 900, the first mainframe built from scratch with e-business as its primary function, enabling thousands of servers to operate within one box.
More recently, IBM has only extended its mainframe leadership. The latest zSystems mainframes can execute more than 1 trillion secure web transactions per day and feature a cloud-native architecture and world-leading central processing units to provide the high-volume, real-time processing that’s needed for artificial intelligence in financial fraud detection.
System/390 proved that the mainframe, far from being a technological dinosaur, would remain a key component of many large organizations’ computing strategies, particularly in areas such as e-commerce, the airline industry, healthcare, insurance, banking and financial services. Today, mainframes handle 90% of all credit card transactions and are used by more than 70% of Fortune 500 companies. All of the top 10 insurers worldwide and 44 of the top 50 banks use IBM mainframes.
In 2002, Alsop, the InfoWorld pundit, eventually admitted the error of his prediction. “It’s clear that corporate customers still like to have centrally controlled, very predictable, reliable computing systems,” he wrote, “exactly the kind of systems that IBM specializes in.”
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