The main reason why the IBM iSeries (AS/400) system is not the dominant server that it should be is because of fear of being tied into IBM. Most people are today expensively tied into Microsoft but that has happened over a long period and is not the same thing as making a decision over a significant investment at a specific point in time.
However there is another problem with the AS/400 and that is the availability of applications. When all is said and done a bad system (Windows) with applications is more successful than a good system (OS/2, Mac) without them. Actually the problems of applications for the AS/400 were a mixed bag. In the earlier days the system was targeted at data processing for which there was a healthy choice of applications, but as the client/server concept grew, with a wider range of applications, including office and Web functions, application developers favoured Unix and Windows. Again the AS/400 was seldom left behind but the choice of applications was limited. So the AS/400 operating system was enhanced to support "guest" operating systems such as AIX or Linux, so that other applications could be supported alongside native AS/400 applications. This was effectively a network in a box so that for a Unix application to access AS/400 databases a client/server approach was adopted. Of course the AS/400 supported PCs, Lan connected, as any server, but it was held up in the first place by IBM's insistence on token ring and the long delays in supporting Ethernet and native TCP/IP communications protocols. Again no problem today but all adding up to stop the AS/400 becoming the server of choice.
When IBM introduced the extended support for the other applications they tried to change the image by renaming the AS/400 the iSeries, apparently with little effect on sales, although the extended functionality pleased the established AS/400 users. And so we come to the latest incarnation, the i5 with i5/OS. It is a major step forward and makes the machine even more the ideal server, but quality has never been the issue, so can IBM get the message across this time? And what is that message?
First the hardware. The iSeries uses IBM's Power processor, not an Intel one. The current version, Power5, is a major advance in that as well as a performance increase it has a significant reduction in power consumption. For the iSeries specifically this means that rack mounting can now be used on some models. The Power processor is often perceived as an IBM-only processor (AIX and the pSeries as well as iSeries) but it powers the Apple machines and more significantly the Microsoft X-box. It is a 64-bit processor and OS/400 was by far the easiest operating system to adapt to 64-bit, far easier and more successfully than Unix. Microsoft have naturally favoured the 64-bit Intel processor for the development of 64-bit Windows (Longhorn), but following on from the X-box it is a strong likelihood that Longhorn will also support Power processors. There could well create a war between Intel and IBM for the 64-bit processor market, particularly since the Intel processor has been reported as suffering from reliability problems (the Mars Rover project opted for Power). The big difference between the Intel and the Power architectures is that the former has evolved from a single-threaded desktop requirement while the Power architecture was invented to support multi-threading. It is this rather than raw MIPS that makes Power a more potent server, and probably games machine, processor.< BR>
Martin Healey, pioneer development Intel-based computers en c/s-architecture. Director of a number of IT specialist companies and an Emeritus Professor of the University of Wales.