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7.02 min to readPublisher Advisory Services

ILMT: how to start enjoying the benefits of sub-capacity licensing

Randy BalSolution Consultant for IBM Software
Asset Management

Many organizations make use of IBM software programs and some also struggle with IBM’s licensing scenarios and metrics. IBM provides various different metrics for licensing and measuring usage of its software programs.

The most common used metric is the Processor Value Unit (PVU). A Processor Value Unit (PVU) is a unit of measure used to differentiate licensing of software processor technologies (defined by Processor Vendor, Brand, Type and Model Number). All supported processor technologies by IBM can be found in the PVU Table.

An end user can deploy the IBM software program licensed by Processor Value Unit in two different scenarios:

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

If you decide to license at the full-capacity of a server, you must obtain PVU licenses sufficient to cover all activated processor cores in the physical hardware environment on which the IBM software program is installed.

If you decide to license at the sub-capacity of a server, you must comply with a number of specific Virtualization Capacity License Counting Rules which include the use of IBM’s License Metric Tool (ILMT).

This article provides an introduction about the benefits and drawbacks of ILMT. Further articles on how to install, configure and run software inventory reports in a complete and accurate manner will follow.

The benefits of ILMT

The biggest benefit of using ILMT is obviously that end user organizations can take advantage of only licensing the sub-capacity of a server. As a general rule of thumb, installing and running IBM software at the sub-capacity of the full processor core capacity of a server usually lowers license usage and as such the license and associated support costs.

To be eligible for sub-capacity licensing, the proper installation, configuration and use of ILMT is required. This includes the use of a predefined set of hardware and software scanners. ILMT can be obtained for free with every purchase of IBM Software via Passport Advantage. ILMT provides an overview of the installed software, of where it is installed and how it is being used within your organization.

Is ILMT mandatory?

You are free to choose if you use ILMT when licensing at full-capacity, but the use of ILMT becomes mandatory for sub-capacity licensing. Although there are some exceptions, ILMT is almost unavoidable when IBM software is used in a virtual infrastructure. In today’s IT landscape, almost any organization is making use of virtualization technologies. As such, in practice, 99% of all the end users would like to only license the sub-capacity of a server (to reduce the license and support costs) and are therefore required to make use of ILMT. The requirements for sub-capacity licensing and the use of ILMT can be found in the International Passport Advantage Agreement.

Contractual requirements

IBM allows end users to license only the sub-capacity of a server if – in general – a number of contractual conditions are being met, including the following major requirements:

ILMT Installation:

  • You agree to install and configure the latest version of ILMT within 90 days of your first deployment of the PVU licenses for the IBM software program
  • You will promptly install new versions, releases, modifications, or code corrections (fixes) of the ILMT that IBM makes available
  • You will subscribe to the IBM Support notifications in order to be notified when such fixes become available

ILMT Reporting:

  • You agree to collect deployment data for each PVU licensed IBM program
  • You are required to prepare at least once per quarter (and retain for a period of not less than 2 years) reports as per the audit reports example
  • You are required to manually manage and track your licenses for all instances where ILMT is not used (and for all non PVU based licenses)
  • You will assign a person in your organization with authority to manage and promptly resolve questions on audit reports or inconsistencies between report contents, license entitlement, or ILMT configuration.

The failure to generate audit reports or provide audit reports to IBM (during the course of an audit) will lead to charging under full-capacity the total number of physical processor cores activated and available for use on the server.

Technical drawbacks

The most common heard complaint is that ILMT is seen as ‘yet-another-software-scan-tool'. A system administrator needs to install ILMT and BigFix and a software asset manager needs to manage the software inventory process. One of the biggest technical concerns heard is typically the impact it may have on the infrastructure due to the additional permissions which are required to be able to scan and access software, hardware and virtual infrastructure. In order to get a better understanding of these technical drawbacks, let us first explain the two main components (ILMT and BigFix) that are involved in more detail.

BigFix platform

ILMT is a component of the BigFix platform and is used to manage and execute software and hardware discoveries. BigFix itself is a systems-management software product for managing large groups of computers (or endpoints) running almost all (mobile) operating systems. BigFix provides system administrators - among others - with patch management, software distribution, operating system deployment, network access protection and software and hardware inventory functions. Both ILMT and the BigFix platform itself, are free of charge for IBM customers.

IBM also offers BigFix Inventory (BFI). BigFix Inventory is a separately licensable product and can be used as a replacement of ILMT. The major difference between the ILMT and BigFix Inventory is that ILMT is limited to IBM software and free of charge, whereas BFI’s software catalogue contains more than 1000+ other software publishers as well but is required to be licensed separately.

This picture provides a graphical overview of the relation between the different components of an ILMT/BigFix installation:

BigFix platform

Supported technologies

ILMT and BigFix support the use of a wide range of different operating systems, virtualization technologies and cloud platforms such as Windows 2016, VMWare 6, Docker, Hyper-V, Azure, Amazon EC2 and Google. In order to be able to obtain and scan the required hardware and software data, ILMT needs access and permissions to these different operating systems, virtualization technologies and/or cloud platforms. All requirements, installation guide and tutorials can be found in IBM's Knowledge Centre.

Risks and warnings

ILMT is not an “install once and you are done” tool. ILMT needs to be actively managed to ensure a complete and accurate view of your software deployments to remain compliant with your sub-capacity license requirements.

The maintenance of your ILMT environment includes, among others:

  • Collecting up-to-date software deployment information, once a week
  • Collecting hardware and virtual infrastructure information every 30 minutes
  • Creating and provisioning quarterly and 2-year reports on request by IBM
  • Maintaining ILMT to the latest version
  • Maintaining a complete and accurate software inventory by applying bundling, exclusions and suppressions
  • Monitoring and controlling your license utilization

Only if all the above requirements are met, you can take advantage of sub-capacity licensing. Failure on one or more of the above listed tasks will increase the risk of being charged to license the full-capacity of the server. To manage the risks, ILMT includes tools to schedule reporting, alert functions on risks and thresholds reached etc.

ILMT Health Check and ILMT Managed Services

A complete and accurate management of the ILMT environment is required in almost any end user organization making use of IBM software. During our 20+ years of experience, we noticed that many organizations lack the appropriate knowledge, experience and/or resources to manage their ILMT environment correctly in house. And that’s understandable, but it often leads to situations where end users need to license the full-capacity of a server after an audit or verification by IBM or one of its third-party audit firms.

In order to help our customers to get a better overview of their IBM software and ILMT environment, we designed the ILMT Health Check service.

During this health check we will verify the:

  • State of the deployment: Review of your hardware and software scans
  • Completeness: Review of the completeness of BigFix, ILMT and your Software Inventory
  • Accuracy: Review of your ILMT setup and suggestions to improve the Software Inventory accuracy
  • License utilization: Recommendations to improve and track license utilization


We also designed a managed service to maintain your ILMT environment on an ongoing basis. The delivery of this managed service means that we will take the responsibility on your behalf to install, configure, manage and maintain your ILMT environment in a complete and accurate manner so that you can enjoy the actual cost avoidance and cost saving benefits of being eligible for sub-capacity licensing.


Ask for advise!

For more information on our ILMT Health Check or ILMT Managed Services, please don't hesitate to contact us!

Ask for advise!

For more information on our ILMT Health Check or ILMT Managed Services, please don't hesitate to contact us!



Randy Bal
Solution Consultant for IBM Software

Specialist for IBM Software Licensing and IBM License Metric Tool