Implementing IBM License Metric Tool (ILMT) for SAM: A Complete Guide
IBM’s enterprise software licensing costs often scale with the number of processor cores utilized by your workloads.
To control these costs on virtualized servers, IBM offers sub-capacity licensing – but only if its IBM License Metric Tool (ILMT) is properly deployed and configured. ILMT is IBM’s mandated tool for tracking processor usage (measured in PVUs) across distributed systems.
Without ILMT, even a lightly used VM can incur licensing for the host’s full capacity, leading to hefty, unnecessary charges. For an overview, read our guide to IBM Software Asset Management Strategies.
For IBM customers, failing to implement ILMT essentially forfeits sub-capacity savings and risks facing an audit where all servers are counted at full capacity.
This guide provides a strategic roadmap for implementing ILMT and integrating it into your Software Asset Management (SAM) practice. It covers the ILMT requirements for compliance, a step-by-step deployment process, common pitfalls to avoid, and best practices to leverage ILMT data.
By following these insights, CIOs, IT asset managers, and procurement teams can avoid compliance penalties, optimize IBM software spend, and fully benefit from IBM’s flexible licensing without audit surprises.
What is ILMT and Why It Matters
IBM License Metric Tool (ILMT) is IBM’s official tool for tracking processor-based usage of its software.
Provided at no extra cost, ILMT automatically discovers IBM software across your environment and measures each installation’s Processor Value Unit (PVU) consumption over time. In simple terms, ILMT tracks the number of processor cores each IBM product utilizes on your virtualized or distributed servers.
The reason ILMT exists is to enable sub-capacity licensing, allowing you to pay only for the portion of a server’s capacity that an IBM product actually uses, rather than licensing the entire physical server.
IBM makes this cost-saving option contingent on deploying ILMT to verify your actual usage. Under Passport Advantage agreements, ILMT is effectively mandatory whenever you want to utilize sub-capacity pricing.
Without ILMT in place and functioning, IBM will default your licensing to full capacity, meaning you’ll be charged for every processor core on the host machine.
This nullifies any virtualization savings and can dramatically increase costs. The contrast between full-capacity and sub-capacity licensing is illustrated below:
| Licensing Mode | License Counting Method | Example Scenario |
|---|---|---|
| Full Capacity | License all physical cores on each host where IBM software runs, regardless of actual use. ILMT is not required under this model. | An IBM application on a VM with 2 cores running on a 32-core host would require licensing all 32 cores (the server’s full capacity). |
| Sub-Capacity | License only the virtual cores (or specific capacity) allocated to the IBM software, rather than the entire host. ILMT must be installed and configured to use sub-capacity. | That same application on a 2-core VM (on a 32-core host) would only require licenses for 2 cores, provided ILMT is monitoring and reporting this usage. |
As shown above, the difference in licensing scope is significant. ILMT is the enabling tool that ensures you only count the cores you truly need to license.
For CIOs and SAM professionals, this translates into major savings in highly virtualized environments.
Beyond compliance, ILMT also provides your team with visibility into IBM software consumption, enabling them to optimize resource allocation and prepare for audits with confidence.
ILMT Compliance Requirements
Sub-capacity licensing is not automatic — you must adhere to IBM’s ILMT compliance rules to qualify for those savings.
IBM’s licensing terms (under Passport Advantage) spell out specific requirements for ILMT usage and reporting. Failing to meet these requirements means that IBM can revert your licenses to full capacity, erasing any cost advantage.
Key ILMT compliance requirements include:
- Timely deployment: Install and start using ILMT within 90 days of your first sub-capacity eligible IBM software deployment.
- Complete coverage: Ensure ILMT covers all servers where IBM PVU-based products run (including all VMs and hosts in distributed environments). Any server running IBM software without ILMT monitoring will be considered to be at full capacity for licensing purposes.
- Regular reporting: Generate ILMT usage reports at least quarterly – IBM expects an “audit snapshot” every three months to document your sub-capacity consumption.
- Archive for 2 years: Retain each quarterly ILMT report for a minimum of two years. If IBM initiates an audit, you will need to produce up to two years’ worth of ILMT reports to prove continuous compliance.
- Maintain currency: Keep ILMT updated to the latest version and ensure its software catalog is up to date. Using an outdated ILMT or failing to apply updates can result in inaccurate data, and auditors may view a significantly outdated ILMT as non-compliant.
IBM formerly allowed a few exceptions for very small environments or unsupported platforms, but those have now been phased out.
In practice, all customers using sub-capacity licensing must deploy ILMT – non-compliance simply isn’t worth the risk. If you cannot produce the required ILMT records, IBM will charge full capacity retroactively – leading to a very painful true-up during an audit.
ILMT Deployment Process
Implementing ILMT for your IBM software environment involves several steps. Below is an overview of the typical deployment process from installation to ongoing reporting:
- Install ILMT in all distributed environments. Set up the ILMT server (usually as part of IBM’s BigFix/ILMT bundle) and deploy the ILMT agent or scanner to all servers running IBM software. Ensure that every machine with IBM PVU-based products is connected to ILMT – this may involve installing agents on each VM or endpoint, or utilizing ILMT’s scanning capabilities across your network.
- Configure ILMT to capture PVU data. After installation, configure ILMT properly to ensure it gathers the correct data. Import the latest IBM software catalog into ILMT to recognize all your IBM products. Schedule regular scans/inventories of your environment. Essentially, tune ILMT to accurately collect processor core usage (PVU) information for each IBM product deployed.
- Integrate ILMT with virtualization platforms. Connect ILMT to your virtualization management systems (e.g., VMware vCenter, Microsoft Hyper-V, IBM PowerVM). These integrations allow ILMT to retrieve host hardware details and track VMs as they move. By integrating with hypervisors, ILMT can accurately attribute virtual cores to physical hosts – a critical step for precise sub-capacity counting.
- Generate and review quarterly reports. Using ILMT, generate official sub-capacity usage reports at least once per quarter (referred to as “audit snapshots”). Don’t just file these away – have your SAM team review each report for accuracy. Verify that all expected software instances are present and that the PVU consumption aligns with your understanding of the environment. Identifying and investigating anomalies now helps avoid surprises later.
- Archive reports and reconcile with entitlements. Save each quarterly ILMT report in a secure repository and retain it for at least two years (to meet IBM’s audit retention requirements). After each reporting period, reconcile the PVU usage ILMT reports with your purchased license entitlements and address any over-use immediately (either by reducing usage or procuring additional licenses). If reports consistently show significantly lower usage than you have licensed, consider optimizing your IBM license holdings and reducing excess licenses at renewal time. This report archival and reconciliation process ensures you remain compliant and audit-ready.
Read our IBM SAM best practices, IBM SAM Best Practices: How to Stay Compliant and Optimize IBM Licensing.
Common ILMT Implementation Pitfalls
Even when companies deploy ILMT, common mistakes often undermine its effectiveness. Being aware of these pitfalls can help you avoid them:
- Not covering all virtualized servers: A common mistake is installing ILMT without including every server or VM where IBM software runs. If even one VM with IBM middleware is left outside ILMT’s scope, that machine’s usage won’t be captured – and IBM will consider it unmonitored (subject to full-capacity licensing). This often happens in fast-changing environments or hybrid clouds where new instances come online without the ILMT agent. Ensure your ILMT deployment is comprehensive and updated whenever your infrastructure changes.
- Failing to generate or save quarterly reports: Some organizations run ILMT continuously but neglect to generate and archive the required quarterly reports; IBM expects you to produce these sub-capacity snapshots and retain them. If you miss a quarter or fail to save the output, you’re out of compliance. During an audit, not having those historical reports readily available is a serious red flag. Make report generation and archiving a strict quarterly routine.
- Misinterpreting PVU calculations: ILMT data can be misread if your team doesn’t understand IBM’s licensing metrics. For instance, ILMT might indicate a product’s PVU consumption peak for the quarter, which is what IBM is concerned with. Still, someone might mistakenly focus on an average or current usage when reconciling licenses. Additionally, certain IBM products come with bundled components that ILMT lists separately; if you misinterpret these, you could either double-count or overlook license requirements. Always educate your team on how ILMT calculates PVUs (peak usage, PVU-per-core values, bundling rules) to avoid incorrect assumptions.
- Running ILMT but not validating its accuracy: Installing ILMT is not a “set and forget” solution; you must regularly ensure the tool’s data remains accurate. Common issues include missing data from servers where the ILMT agent was never installed or failed to report, outdated software catalogs leading to unrecognized products, or retired systems still listed in ILMT’s inventory. If you don’t validate ILMT findings against reality, you might assume you’re compliant when you actually have gaps. Assign an ILMT administrator or SAM manager to routinely review ILMT outputs, resolve errors (such as broken VM connections or misidentified software), and keep the tool up to date.
Using ILMT for SAM Optimization
ILMT isn’t just a compliance necessity – it’s also a valuable source of data for optimizing Software Asset Management. By analyzing ILMT reports, you can reconcile your IBM license entitlements against actual usage and identify areas of inefficiency.
This helps ensure you’re not over-paying for licenses you don’t use (over-licensing) and not at risk of shortfalls where usage exceeds entitlements (under-licensing).
Use ILMT data to drive smarter renewal and procurement decisions. Review the past year of ILMT usage for each IBM product before negotiating renewals or new purchases.
If a product consistently uses far fewer PVUs than you’ve licensed, consider negotiating a reduction in licenses or support costs. Conversely, if ILMT shows an increase in usage for a particular software, plan to budget for additional licenses proactively.
ILMT reports can also strengthen your position in negotiations with IBM. Having concrete usage data shifts the conversation from guesswork to facts, allowing you to challenge renewal quotes and better align entitlements with actual needs.
In short, ILMT is a strategic tool in the SAM toolbox, helping you continuously right-size your IBM license portfolio and avoid spending surprises.
Read the Top 10 Challenges, Top 10 IBM SAM Challenges, and How to Overcome Them.
Checklist – ILMT Implementation Essentials
Use the following checklist to ensure your ILMT implementation covers all the critical bases:
☐ ILMT installed across all relevant environments
☐ PVU data captured accurately
☐ Quarterly reports generated and archived
☐ Reports validated against entitlements
☐ Gaps corrected before IBM review
☐ SAM team trained on ILMT use
FAQs
Q: Is ILMT mandatory for IBM licensing?
Yes – if you want sub-capacity pricing, ILMT is required. Without ILMT, IBM will default to charging for full hardware capacity.
Q: How often should ILMT reports be generated?
At a minimum, quarterly. IBM expects you to produce a sub-capacity usage report at least every three months and to retain at least two years of those reports.
Q: Does ILMT cover cloud workloads?
Not for most cloud scenarios. ILMT is designed for traditional on-premises and VM-based deployments. IBM Cloud Paks and SaaS offerings have their own separate monitoring and compliance tools.
Q: What happens if ILMT is misconfigured?
If ILMT is not set up correctly, you risk IBM treating your deployments as non-compliant. In practice, that means you could be billed at full server capacity despite lower actual usage.
Q: Can ILMT help in renewals?
Absolutely. ILMT data provides a clear picture of your true usage. This supports right-sizing your licenses before renewals, giving you factual leverage to negotiate more favorable terms with IBM.
Read about our IBM Licensing Assessment Service.
