The IBM AS/400 line of servers, first introduced in 1988, is one of the most popular mid-range servers in history. By 1997 IBM had shipped almost half a million AS/400s. The AS/400 became the first choice for companies needing ultra-reliable server systems that offered a lower total cost of ownership when compared to available alternatives, which may have had lower initial costs but required significantly more long-term maintenance expenditure.
The AS/400 line was developed at IBM's Rochester facility under the leadership of computer scientist, Frank Soltis. It was a continuation and development of the System/38 architecture and was developed under the code names Silverlake and Olympic. The line has been continuously advanced over the years to keep it at the cutting edge of technology. In 2000, IBM renamed their mid-range server line to the iSeries as part of its e-Server re-branding. In 2008, IBM consolidated and merged their iSeries and pSeries server lines and re-branded them Power Systems, although they are often popularly still referred to as AS/400s.
AS/400s were a tempting proposition for medium and large enterprises because they offered a vertically integrated IT solution. AS/400 and iSeries servers included almost everything a company needed to run their application software. With competing UNIX and Microsoft based products it was necessary to source the various parts of a complete server platform from different suppliers. The integrated (the i in iSeries stands for integrated) nature of the AS/400 and iSeries minimized setup costs, providing blades, storage, operating system, security software and an active application ecology in one package.
The AS/400s design also made them incredibly flexible and scalable, with an unprecedented degree of future-proofing, which offered some protection from the built in software obsolescence strategies of competing platforms. The AS/400s Technology-Independent Machine Interface meant that when the underlying platforms changed, even as radically as the shift from CISC to RISC processors, the same software would run, ensuring a businesses continuity and confidence in their investments in software purchase and creation.
AS/400s and iSeries servers were specifically designed for the sort of transaction processing that is central to businesses IT needs. They were ideal for running Enterprise Resource Management software and reliable enough that the industry is full of stories of AS/400s that have run for 5 years continuously without ever needing to be re-booted.
AS/400s were also at the forefront of virtualization technology. The iSeries incorporated Logical Partitioning technology which allowed one server to simultaneously run multiple operating systems. Modern servers in this line have processors optimized for virtualization, enabling many hundreds of virtual machines to be run by one unit.
The successors of the AS/400 and iSeries servers are the IBM Power Systems, which continue the tradition of offering integrated solutions for enterprise customers. The cutting-edge Power7-based servers provide businesses powerful and scalable infrastructure with lower space, maintenance, and energy requirements than a server farm built with commodity hardware.