AS/400: the host with the most?

Question: which IBM server range can run applications written for Windows NT and 2000, Novell NetWare, Aix and OS/2 as well as...

Question: which IBM server range can run applications written for Windows NT and 2000, Novell NetWare, Aix and OS/2 as well as its own native operating system, all at the same time?

Answer: the AS/400, or as we must now learn to call it, the iSeries.

The chameleon nature of the iSeries has developed very gradually over the past six years. At launch in 1988, the AS/400 could only run its own native operating system, OS/400. But the IT world was then still very proprietary: Unix had not yet taken off (the RS/6000 was two years away), Windows NT was not yet invented, and Windows itself was a very rudimentary desktop operating system.

IBM did an excellent job in persuading software developers to write for the AS/400 before it was even launched, and at the time of first delivery there were 2500 packages available for the range. The number rapidly increased, and this support from the independent software suppliers (ISVs) was one of the main reasons why the AS/400 sold so well in its first two to three years.

Today, however, ISVs write for Microsoft first and for Unix second, with Linux rapidly becoming an important third platform. IBM can no longer rely on its friends in the software community to keep the AS/400 up to date.

This became clear to AS/400 strategists early in the '90s, and they developed a series of mechanisms allowing the range to run software written for different platforms.

The first step was taken in 1994, when IBM introduced the FSIOP (File Server Input Output Processor). It was one of a number of special purpose IOPs - others were introduced for fax, Raid subsystem support, internet access, and the like. The FSIOP was different, because it ran its own operating system - OS/2 Lan Server - cooperatively with OS/400, with both using the same system resources. Physically it was a plug-in card containing a 66 MHz Intel 486 processor. Up to 16 FSIOPs could be configured.

The FSIOP did not initially attract much attention, as it could only be used to run a relatively unpopular network operating system. But in 1995 IBM added a second FSIOP, capable of running Novell NetWare. This required some tricky engineering, as NetWare at the time made use of MS-Dos, which was nowhere to be found on the AS/400. Nonetheless, this established the AS/400's ability to run mainstream 'foreign' operating systems.

The effectiveness of the FSIOP was enhanced when IBM brought the disks inside the AS/400, as this significantly improved performance.

The FSIOP has since been re-named twice. It became the Integrated PC Server in 1997, and then the Integrated Netfinity Server in 1999 (we can probably expect another new name soon, now that Netfinity has become the xSeries). The technology has been steadily enhanced, and the latest version, announced in May, has a 700MHz Pentium III processor.

Probably the most important development, however, came in 1998, when the ability to run Windows NT was added (Windows 2000 has become an option now on the latest version). Since then, between a fifth and a quarter of all AS/400s installed have had at least one of these add-in co-processors. Customers have been using them mainly to run file, print, and directory applications, though last year Web serving started to become popular as well.

Some of the new eServer offerings announced at the beginning of last month take advantage of the Integrated Netfinity Server. The Siebel Systems product, for example, runs partly under OS/400 and partly under Windows NT.

The Integrated Netfinity Server does have limitations. It only contains a single processor, and therefore is not powerful enough to run the new enterprise-level applications being developed for Windows 2000. According to Catalyst Solutions Group head of technology strategy Ben Schofield, 'it is not designed for that; it's not meant to be a Teraplex-type server. It's for file and print and directory services.'

Furthermore, upgrading it is difficult for IBM as each one has to be specially engineered, and then tested. So IBM's cards tend to lag a few months behind the Intel state of the art.

As a result, IBM has committed to introducing the ability to connect an external Netfinity server operating in the same way as the internal card, with the connection being via the HSL (High Speed Link). This will allow users to connect the latest Netfinitys as soon as they come out, and also to connect multiple processor systems for more power-hungry applications.

The number of Integrated Netfinity Servers supported has remained at 16 since the original FSIOP was introduced. IBM has committed in future to extend this first to 24, and then to 32.

At the beginning of last year IBM added a new dimension to the AS/400 - logical partitioning. This is a mainframe feature which allows you to run different workloads side by side in the same machine, with the partition used for each workload tuned to that workload's performance requirements. On the AS/400, users can tune partitions for interactive or e-business performance.

Partitioning can be used for server consolidation; you can run multiple virtual servers within the same physical machine. This can provide savings in both direct cost (there is still just a single licence for the entire physical machine, no matter how many copies of OS/400 it is running) and in management time.

The logical partitioning in the iSeries is as yet primitive in comparison with System 390 PR/SM (let alone the zSeries Intelligent Resource Director announced earlier this month), but is advanced compared with anything outside the mainframe world.

Each partition is created from one or more processors complete with memory, and is allocated its own disks. They have a separate system name.

Different time zones

One advantage of this is that the partitions can be configured to run in different languages or different time zones. According to worldwide marketing manager for Server Consolidation Ted Scharf, 'before, if you had different systems in different time zones, with different dates and different languages, you had to have separate machines; now you can consolidate onto one'.

Partitions can be connected internally for high performance, using OptiConnect software, or can be connected externally via Lan or Wan adapters.

One of the benefits of partitioning is that it allows you to separate a test workload from the production work, so that any problems do not impact the mainstream processing. With V4R5 of OS/400 IBM has extended this advantage by allowing you to run V4R4 in one partition, and V4R5 in another.

Logical partitioning is the means IBM has chosen to allow running of Linux on iSeries. This means that the iSeries will be able to run multiple copies of Linux, and so can be a vehicle for NT server consolidation in this respect too.

Disappointingly, though, no further details were forthcoming at the iSeries launch at the beginning of this month. The platform remains the only one of the eServer brands that cannot currently run Linux, and it will be well into next year before it can.

The final method of running applications not available on OS/400 was announced at the start of this year. This is Pase, for Portable Application Solutions Environment. Pase is a new OS/400 component that provides a subset of Aix runtime functionality.

It does so by taking advantage of the fact that AS/400 and RS/6000 processors are physically identical. Each can be set to run in AS/400 or RS/6000 mode. At one time the switch setting was hard wired, but on more recent models it is soft coded. As a result, an AS/400 processor can be set to run in RS/6000 mode, and then back again.

Pase allows you to recompile an Aix application for the AS/400. When it then runs, it changes the soft switch setting of the processor to RS/6000 mode, and when it has finished it changes it back again. A major benefit being there is no emulation overhead. According to IBM marketing communications manager Paul Fryer, 'the AS/400 is not running Aix, so the performance is almost identical'.

Pase applications can use AS/400 file systems and DB2, and can be integrated with Java, Lotus Domino, and ILE (Integrated Language Environment) applications. So the iSeries is today a very versatile machine, with the ability to run many applications that are not available for OS/400. Its biggest weakness is the inability, yet, to run Linux, which does weaken IBM's argument for using the iSeries in e-business.

But the existing loyal user base has far more options for taking advantage of new applications than it had a few years back. With Linux and four-way Netfinitys coming on stream next year, this process is set to continue. l

BOXHEAD: Timeline BOXTEXT: Timeline

May 94 - FSIOP introduced with 66 MHZ 486 processor, running OS/2 Lan Manager

Jun 95 - NetWare FSIOP launched

Mar 97 - FSIOP re-named Integrated PC Server and uprated to 133MHz Pentium

Feb 98 - Windows NT capability added to Integrated PC Server

Mar 99 - Integrated PC Server re-named Integrated Netfinity Server,

and uprated to 333 MHz Pentium II

May 99 - Logical partitioning introduced with OS/400 V4R4

Jan 00 - Pase introduced, providing ability to run Aix applications

May 00 - 700MHZ Integrated Netfinity Server launched; ability to run Windows 2000 added; ability to run different versions of OS/400 on same machine introduced; number of logical partitions increased from 12 to 24

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