> I just read your article at http://www.esj.com/news.asp?ID=5151. I have to > say I was disappointed at how inaccurate it was in a number of regards. > You wrote "IBM Corp. has offered Linux as an option on its z/Series > mainframe for nearly two years, but there was a catch: Linux ran in a > partition managed by z/OS." This is completely off base. From "day one," > Linux/390 could be run in three different modes (which is still the case > today):
> 1. As the _only_ operating system on the machine, often referred to as "on > the bare metal." Technically it would run. If we extend the definition of 'could' to include what was practical, bare metal wasn't (and still isn't) an option. > 2.In a logical partition of the machine (LPAR mode). Other operating > systems (such as OS/390, VSE, z/OS, etc.) could be running in other LPARS on > the same machine, but they had no direct role in how Linux/390 operated in > its own LPAR. Not far off the above, to be honest. Even an IFL is too expensive to run only one copy except in very special circumstances. > 3. Under VM (now z/VM) as a "guest" operating system. Given the nature of > VM, this could mean one Linux/390 guest, up to thousands. The limit is > determined by the amount of hardware resources you make available to VM. Which is the only option on the new offering. > IBM later introduced a different form of their processors (named "Integrated > Facility for Linux" or IFL processors) that would only run Linux/390, and > later, Linux/390 under z/VM 4. These processors were about one-third the > price of the "normal" processors, making it very attractive to run > Linux/390. The only "catch" is that you had to order at least one "normal" > processor per system for technical reasons (IBM hadn't yet re-written their > machine management software to run on IFL processors). Ergo - you 'needed' z/OS. The number of accounts running pure VM or VM/VSE on zSeries hardware is not great and for the vast bulk z/OS was a real prerequisite. > With the introduction of the z800 processor series, this is no longer the > case. A site can order a system that has only IFL processors in it, and no > "normal" processors. This means that they will only be able to run > Linux/390 on it, or Linux/390 under z/VM. They will not be able to run > OS/390 or z/OS, or VSE on it, not even as z/VM guests. No, as I read the Announcement Letter, z/VM is not optional on a system-wide basis. Whether you can define 'bare metal' LPARs is still unclear to me. The RedBook link from the Announcement Letter doesn't work. > IBM Marketing is being somewhat disingenuous when they claim that the new > z800 systems don't require staff with mainframe operating system skills. Dunno yet - we haven't seen just how preconfigured and locked down the z/VM system is. What if IBM retain all the passwords to the privileged machines? > That may be true if they're only running Linux/390, and not z/VM. If they > want to have more than 15 copies of Linux/390 running on a given system, > that will require them to run z/VM, and they'll need staff with z/VM skills > to get the kind of performance that is worth the money they paid for the > hardware and software. I can only find '15' in the press release and in conjunction with the ISeries. The Offering specifically includes z/VM - I don't think it will prove optional and I think that's what you're supposed to use for 'virtualisation'. The Announcement Letter talks about LPAR move functionality and suchlike, but doesn't explicitly say how many are supported. > When you write "Cutting out z/OS also cuts much of the cost of the > mainframe. McCaffrey says the cost of a Linux mainframe with a three-year > maintenance contract and a three year software subscription to z/VM is > nearly half the cost of a similar z/OS mainframe package." IBM's message is > being miscommunicated or misunderstood here. Since z/OS is not being "cut > out" of the picture (it was never "in the picture"), the difference in > pricing between a z800 and a z900 is mostly due to the fact that the z800 > has only IFL processors in it, which are one-third the price of the > processors in the z900 system. The price of a box with one processor is not just the price of the processor. A z800 containing one IFL is not the same price as an IFL which is added to an existing z900. I would expect a z800 uniprocessor in 'full function' mode to be about the same price as a z800 uniprocessor Linux-only machine - the difference is an essentially 'free' OTC licence for z/VM with three years' subscription in exchange for the 'crippling' of the microcode to make it into a Linux-only box. -- Phil Payne http://www.isham-research.com/quattro +44 7785 302 803 +49 173 6242039
