isham research
(This discussion has been overtaken by events. The current version will be found here)
One of the major issues IBM faces in the medium and long term with its zSeries (Freeway) mainframe systems is the complete and utter lack of affordable development platforms for small ISVs. A proposed low-end 64-bit system - codenamed 'Flagstaff' - was cancelled in September 1999 and many have been waiting for a replacement to be announced.
The 'Flagstaff' replacement - apparently officially known as 'Raptor' but usually referred to here as 'Subway' - will be built for IBM by Hitachi and will use a five-way MCM to deliver one to three G7 processors for customer use. One processor is reserved as a SAP and one as a spare. Since this system is also intended for the Japanese VOS domestic market, IBM will have to restore the VOS functionality they deleted in the move from G6 to G7 - a good opportunity to fix a few other bugs in the design, which has already seen a number of disruptive microcode upgrades. Not good for a 'continuous computing platform'.
Subway, however, would start somewhere around 80 MIPS. The G7 processor - even before the extensive rework it will have - is just too powerful for small and medium System/390 mainframe users. MCM packaging is also too expensive for single-chip systems. As Dan Colby - head of IBM's System/390 efforts - said to an auditorium full of IBM Business Partners at Partnerworld 2001 in Atlanta - "Below 60 MIPS the only solution is emulation."
By the middle of 2002, this 60 MIPS will be 80 MIPS. At present, the only commercial System/390 emulation game in town is Fundamental Software and its partners with their FLEX-ES software - the same software as IBM's withdrawn x/EFS. Both Cornerstone Systems and T3 Technologies now have Business Partners in Europe and NMC has a demonstration and competence centre in Hamburg for Northern Germany, Scandinavia, etc. There is also a mailing list for FLEX-ES users.
Other IBM commercial S/390 emulation efforts include the Windows-based[1] UMX Technologies and Platform Solutions - the former has no significant installed base or income other than venture capital - it is now in its third round of venture capital funding with current management planning to exit by selling the company. Platform Solutions is developing a System/390 emulator for incorporation into its own server systems and has currently no plans for either VM or zArchitecture support.
One other offering - the Hercules open source emulator - remains a curiosity limited to amateur retro-computing, since IBM has made a business decision not to license its commercial operating system software on the platform.
Contrary to a mythology fostered by interested parties, there is NO provision for copying licensed software for "disaster recovery testing" or any other purpose in IBM's licenses. In fact, loading mainframe software onto a PC is expressly forbidden:
LICENSE INFORMATION
The Programs listed below are licensed under the following terms and conditions in addition to those of the International License Agreement for Non-Warranted Programs.
Program Name: IBM SMP/E for z/OS and OS/390 V3R1
Program Number: 5655-G44
Authorization for Use on Home/Portable Computer: 2
EXPLANATIONS OF TERMS:
Authorization for Use on Home/Portable Computer:
"1" means that the Program may be stored on the primary machine and another machine, provided that the Program is not in active use on both machines at the same time. "2" means that you may not copy and use this Program on another computer without paying additional license fees.
Obviously "1" - making but not using a copy - covers the disaster recovery scenario. "2" - not copying - applies to much software that would never be used on such a situation, but which is essential for maintenance and support of a stable production system.
IBM has more recently made it clear that publication does not confer rights:
IBM may have patents or pending patent applications covering subject matter in this document. The furnishing of this document does not give you any license to these patents
SA22-7832-02 zArchitecture Principles of Operation
One major differentiator in the emulation world is hardware. Fundamental Software is somewhat mis-named; their products also include PCI channel cards and a communications adapter card. Although emulation runs much better using internal disks and emulated tapes, many small and medium users need to attach peripheral devices - especially impact printers. In some cases, applications have already been moved off the mainframe and what remains is tied there by a particular peripheral requirement - an investment in turn-around documents, for instance.
IBM's NUMA-Q product was a stopgap (FLEX-ES was announced for Dynix-ptx on the NUMA-Q by Sequent a year before IBM bought the company) and proved - as predicted here - to be the wrong platform. Already premium-priced because of its potential scalability and still only 'generally available' with 700MHz processors, IBM had already reversed its earlier intention to support Windows Data Center Server on the xSeries x430 platform. IBM's 1GHz xSeries (Netfinity) range, in particular, now employs a lot of ex-mainframe technology and OS/390 itself is still one of the world's most stable and secure operating systems.
Emulation opens other possibilities. Not only does it lower the entry cost for ISVs wishing to develop for or port applications to Linux/390 and/or z/OS, it also allows a mainframe environment to be run on a laptop. Demonstrating System/390 applications has always been problematic; it is hard to do it effectively over a dial-up link - either the entire system has to be installed at the potential customer's site or all of the customer's decision makers have to journey to another demonstration data centre. The latter can be a little like herding cats. Only rarely can applications be demonstrated satisfactorily via dial-up links. Now, a humble IBM ThinkPad can run z/OS or Linux/390 under Linux - and fit in a salesman's briefcase.
It's obvious now that other emulations must come. With IBM having declared support for Linux on all platforms, a 64-bit Linux port of FLEX-ES would provide System/390 compatibility on all IBM's servers. There is a distinct need for 64-bit z/Architecture development systems, and also both 31-bit and 64-bit IBM mainframe architectures running on medium-sized systems under 64-bit Linux.
Problems remain in the areas of peripheral compatibility - the channels available at present do not permit the attachment of external DASD - and software charging. In most cases, emulation of System/390 DASD on UNIX file systems is no problem - capacities are more than adequate and performance better by a factor of two or three. Current data centre storage subsystems from IBM, HDS and EMC all support open systems attachment, so they can be used with an emulated system, if in a slightly different way.
Software charging is another issue - if emulation is artificially limited to 8 MIPS, ESL licensing can be used - but unconstrained systems present a problem. Fractional GOLC (1/3rd of Multiprise 3000 H30 GOLC per Intel processor) is one approach, but many IBM products do not have GOLC defined and some ISVs don't recognise GOLC at all. The situation is complicated further by continual changes in xSeries server platforms - 1/3rd of Multiprise H30 GOLC was originally released for Intel processors up to 1GHz and availability of these is slowly becoming a problem with shipments of 1.13GHz and 1.26GHz being preferred.
(Not to be confused with the FlexServer output management system.)
[1] Although the 'description' metatag on the UMX Technologies home page states that VMF also runs under Linux.