Agenda
- Introduction to IBM License Metric Tool (ILMT) and its purpose
- Risks of poor ILMT maintenance
- Infrastructure overview
- Architecture and component interactions
- Questions and answers
Introduction to ILMT and its purpose
- Free-of-charge IBM software discovery tool from IBM.
- Mandatory for use with sub-capacity based licensing (PVU, VPC, RVU-MAPC).
- Customers must maintain documentation for at least two years to demonstrate ongoing compliance with sub-capacity licensing terms.
- Alternatives to ILMT: FlexeraOne, BigFix Inventory, and FlexNet Manager (addendum and written permission from IBM required).
Risks of poor ILMT maintenance
Two things go wrong when ILMT isn't maintained properly:
- Loss of sub-capacity savings — higher true-ups at renewal.
- Higher publisher audit risk and financial penalties.
Scenario 1: no ILMT agent on the server
Without an ILMT agent on a host, IBM will not accept a sub-capacity claim for that host. You are billed for the full physical capacity — every core — even though the VM is only using a slice.
| Metric | Sub-Capacity (with ILMT agent) | Full-Capacity (no ILMT agent) |
|---|---|---|
| VM vCPUs assigned | 4 vCPUs | Full host counted |
| Physical host cores | Not counted | 16 physical cores |
| PVU per core (Intel i7) | 70 PVUs | 70 PVUs |
| Total PVUs charged | 4 × 70 = 280 PVUs | 16 × 70 = 1,120 PVUs |
| Cost per PVU | $1,000 | $1,000 |
| Total licensing cost | $280,000 | $1,120,000 |
| Cost difference | — | +$840,000 additional cost |
| Publisher audit | Sub-capacity accepted | No ILMT agent → forced to license full capacity |
Scenario 2: ILMT agent installed, but the tool has errors
The agent is there, but something else is broken — a VM manager connection has failed, so ILMT can't accurately identify the underlying processor. It falls back to a higher PVU rating per core, and your sub-capacity cost goes up.
| Metric | Sub-Capacity (ideal scenario) | Sub-Capacity (broken VM manager connection) |
|---|---|---|
| VM vCPUs assigned | 4 vCPUs | 4 vCPUs |
| Physical host cores | Not counted | Not counted |
| PVU per core (Intel i7) | 70 PVUs | 120 PVUs |
| Total PVUs charged | 4 × 70 = 280 PVUs | 4 × 120 = 480 PVUs |
| Cost per PVU | $1,000 | $1,000 |
| Total licensing cost | $280,000 | $480,000 |
| Cost difference | — | +$200,000 additional cost |
| Publisher audit | Sub-capacity accepted | Broken VM managers → forced to license increased capacity |
Infrastructure overview
ILMT can be deployed in two ways.
Agent-based (BigFix)
- Most common deployment option.
- Simple to operate and troubleshoot.
- Well documented and supported.
- Greater administrative control.
- Supports hybrid discovery (agent and agentless).
- Platform limitation: no agent for IBM i (AS400).
Agentless (disconnected)
- Newly introduced approach.
- Limited documentation and guidance.
- Relies on third-party tools.
- Reduced administrative control.
- Effective in restricted network environments.
- Supports IBM i (AS400) discovery.
Architecture and component interactions
Agent-based (BigFix)
BigFix agents (BF Agents) are installed on each managed endpoint across the supported OS platforms. They report to the BigFix Server App, which is paired with the BigFix Console and BigFix databases. The BigFix Server App feeds the ILMT Server App, which sits between the ILMT Web UI, the ILMT database, and the VM manager (e.g., Hyper-V) used to reconcile physical-host topology.
Agentless (disconnected)
Multiple disconnected scanners collect discovery data from endpoints and deliver it into the ILMT Server App directly. From there the picture looks the same as agent-based: the ILMT Server App drives the ILMT Web UI, ILMT database, and VM manager connection. There is no BigFix layer in between.
Getting ILMT right
The difference between an ILMT deployment that protects sub-capacity savings and one that quietly costs millions is operational: coverage of every eligible host, healthy VM manager connections, and quarterly reports actually generated and retained. If you're standing up ILMT for the first time, cleaning up an inherited deployment, or preparing for an IBM audit, get in touch.