Software Licensing for IBM System z Distributed Linux Middleware

DancingDinosaur can’t attend a mainframe conference without checking out at least one session on mainframe software pricing by David Chase, IBM’s mainframe pricing guru. At IBM Enterprise2014, which wraps up today, the topic of choice was software licensing for Linux middleware. It’s sufficiently complicated to merit an entire session.

In case you think Linux on z is not in your future, maybe you should think again.  Linux is gaining momentum in even the largest z data centers. Start with IBM bringing new apps like InfoSphere, BigInsights (Hadoop), and OpenStack to z. Then there are apps from ISVs that just weren’t going to get their offerings to z/OS. Together it points to a telltale sign something is happening with Linux on z. And, the queasiness managers used to have about the open source nature of Linux has long been put to rest.

At some point, you will need to think about IBM’s software pricing for Linux middleware. Should you find yourself getting too lost in the topic, check out these links recommended by Chase:

To begin, software for Linux on z is treated differently than traditional mainframe software in terms of pricing. With Linux on z you think in terms of IFLs.  The quantity of IFLs represent the number of Linux engines subjected to IBM’s IPLA-based pricing.

Also think in terms of Processor Value Units (PVUs) rather than MSUs. For a pricing purposes, PVUs are analogous to MSUs although the values are different. A key point to keep in mind: distributed PVUs for Linux are not related to System z IPLA value units used for z/VM products. As is typical of IBM, those two different kinds of value units are NOT interchangeable.

Chase, however, provides a few ground rules:

  • Dedicated partition
    • Processors are always allocated in whole increments
    • Resources are only moved between partitions “explicitly” (e.g. by an operator or a scheduled job)
  • Shared pool:
    • Pool of processors shared by partitions (including virtual machines)
    • System automatically dispatches processor resources between partitions as needed
  • Maximum license requirements
  • Customer does not have to purchase more licenses for a product than the number of processors on the machine (e.g. maximum DB2 UDB licenses on a 12-way machine is 12)
    • Customer does not have to purchase more “shared pool” licenses for a product than the number of processors assigned to the shared pool (e.g. maximum of 7 MQSeries licenses for a shared pool with 7 processors). Note: This limit does not affect the additional licenses that might be required for dedicated partitions.

With that, as Chase explains it, Linux middleware pricing turns out to be relatively straightforward, determined by:

  • Processor Value Unit (PVU) rating for each kind of core
  • Any difference for different processor technologies (p, i, x, z, Sun, HP, AMD, etc—notice that the z is just one of many choices, not handled differently from the others
  • Number of processor cores which must be licensed (z calls them IFLs)
  • Price per PVU (constant per product, not different based upon technology)

Then it becomes a case of doing the basic arithmetic. The formula: # of PVUs x the # of cores required x the value ($) per core = your total cost.  Given this formula it is to your advantage to plan your Linux use to minimize IFLs and cores. You can’t do anything about the cost per PVU.

Distributed PVUs are the basis for licensing middleware on IFLs and are determined by the type of machine processor. The zEC12, z196, and z10 are rated at 120 PVUs. All others are rated at 100 PVUs. For example, any distributed middleware running on Linux on z this works out to:

  • z114—1IFL, 100 PVUs
  • z196—4IFLs, 480 PVUs
  • zEC12—8 IFLs, 960 PVUs

Also, distributed systems Linux middleware offerings are eligible for sub-capacity licensing. Specifically, sub-capacity licensing is available for all PVU-priced software offerings that run on:

  • UNIX (AIX, HP-UX, and Sun Solaris
  • i5/OS, OS/400
  • Linux (System i, System p, System z)
  • x86 (VMware ESX Server, VMware GSX Server, Microsoft Virtual Server)

IBM’s virtualization technologies also are included in Passport Advantage sub-capacity licensing offering, including LPAR, z/VM virtual machines in an LPAR, CPU Pooling support introduced in z/VM 6.3 APAR VM65418, and native z/VM (on machines which still support basic mode).

And in true z style, since this can seem more complicated than it should seem, there are tools available to do the job. In fact Chase doesn’t advise doing this without a tool. The current tool is the IBM License Metric Tool V9.0.1. You can find more details on it here.

If you are considering distributed Linux middleware software or are already wrestling with the pricing process, DancingDinosaur recommends you check out Chase’s links at the top of this piece. Good luck.

DancingDinosaur is Alan Radding. Follow DancingDinosaur on Twitter, @mainframeblog. You can check out more of my work at

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