4.13 min to readPublisher Advisory Services

IBM Sub-Capacity Eligibility – what does it mean in practice?

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Randy BalSolution Consultant for IBM Software
Publisher advisory

In our previous articles we detailed the terms and conditions that allow you to license at the sub-capacity (virtual capacity) of the server for IBM programs using a PVU metric. We explain what sub-capacity eligibility entails and what it means in practice to remain sub-cap eligible.

What is Sub-capacity?

IBM sells its software licenses under different metrics. The most common metric is the Processor Value Unit (PVU). IBM determines the amount of PVU licenses required, depending on the Processor Vendor, Brand, Type and Model Number of the server on which the IBM software programs are installed. IBM provides two different options to deploy an IBM software program using the PVU metric:

  • Physical capacity a.k.a. Full-capacity licensing
  • Virtualization capacity a.k.a. Sub-capacity licensing

In general, licensing the IBM software program at the sub-capacity level of a server is usually preferred as it lowers the required number of licenses and associated support fees. Sub-capacity licensing permits you to take advantage of your virtualization infrastructure and allows you to license only the virtual core capacity assigned to the IBM software program.

IBM license metric tool

To benefit from sub-capacity licensing, you must comply to the terms and conditions defined in the IBM Passport Advantage Agreement. A crucial condition is that you actively maintain the IBM License Metric Tool (ILMT) and you must pursue to:

  • Achieve completeness of your software inventory by
    • Tracking new deployments and removals of IBM programs
    • Creating the correct software bundles
  • Achieve accuracy of your ILMT software inventory by
    • Tracking the assigned processor capacity
    • Using the latest (current) version of ILMT
    • Using supported Operating Systems and Virtual Infrastructure
  • Track, subscribe and examine
    • IBM’s announcement letters
    • Support notifications
    • IBM agreements
    • IBM related websites

IBM provides lots of information supporting you to maintain ILMT. This information includes instructions and videos, a list of frequently asked questions, solutions to common issues, updates to ILMT and changes to support and agreements. It is not only a good practice to subscribe to these sites, it is actually crucial that you do so.

Changes in the list of eligible virtualization technology

One of the high impacting changes shared in December 2019 affected the list of supported Eligible Virtualization Technologies. To be aware of this change you had to track the Passport Advantage Virtualization Capacity (sub-capacity) License web page and had to notice a date change. Have you noticed the date change to 15 October 2019 in the “Use Eligible Virtualization Technologies”?

The consequence of not complying to these updated terms could result in an extremely high financial risk. Even if you have maintained ILMT in a complete and accurate manner.

Two of the most common and impacting changes are:

  • As of April 1st, 2020, IBM will remove support for VMware vSphere 5.x as a sub-capacity eligible virtualization platform, regardless of the Operating System it runs on.
  • Per October 1st, 2020, IBM will remove support for Microsoft Windows 2008 as a sub-capacity eligible Operating System.

The result of these changes is that for any IBM PVU program deployed on an ineligible Operating System or Virtualization Platform, the total amount of available cores in the physical host (full capacity) should be licensed instead of licensing only the virtual core capacity (sub-capacity).

Why is IBM withdrawing technologies from the supported list?

To understand the reason behind IBM’s decision to remove products from the list of supported Eligible Virtualization Technologies, you need to understand the purpose. ILMT continuously interacts with the Operating System and Virtualization Platform to measure the assigned virtual core capacity. To guarantee the result, ILMT and IBM depend on the support of the software publisher in case a conflict arises due to a bug in ILMT, the Operating System or the Virtualization Platform. Since these software publishers (VMware and Microsoft in this case) ended support for their products, IBM can no longer rely on getting support from the software publisher. IBM therefore ends support for those Operating Systems and Virtualization Platforms, 180 days after the support end dates of the virtualization and/or operating system software itself.

What can you do?

Upgrading to a supported release of the Operating System or Virtualization Platform seems like the obvious thing to do. In practice, these are however often postponed due to the following situations:

  • The program is still being used in a legacy environment
  • The IBM program and the dependent components do not support the newer version
  • No active Subscription and Support exist to allow to upgrade the IBM program
  • The new version will present updated terms which will negatively impact the license usage


The biggest concern is that IBM does not notify you directly for relevant changes – ILMT does not warn you when you’re using an ineligible Operating System or Virtualization Platform. If you do not actively track IBM’s notifications, announcement and terms and conditions for relevant information, a high impacting change could go unnoticed until you are surprised by the outcome of an audit.

A yellow wall with a blue sky.

Would like to understand more about our IBM services?

Our license specialists continuously monitor all the changes to IBM’s Terms and Conditions and can support you to manage and monitor you IBM license usage. Do not hesitate to contact us.

Would like to understand more about our IBM services?

Our license specialists continuously monitor all the changes to IBM’s Terms and Conditions and can support you to manage and monitor you IBM license usage. Do not hesitate to contact us.


A man in a floral shirt smiles for the camera.

Randy Bal
Solution Consultant for IBM Software

Specialist for IBM Software Licensing and IBM License Metric Tool