The ILMT sub capacity trap that triggers full capacity charges.

What sub capacity is worth

Sub capacity licensing lets you license only the virtual cores running IBM software instead of the entire physical host. Take WebSphere using four of the 32 cores on a host. Sub capacity licenses that at 480 PVU. Full capacity licenses all 32 cores at 3,840 PVU. Same deployment, eight times the cost, decided entirely by whether your ILMT posture holds.

The four conditions you have to meet

To claim sub capacity, IBM requires all of the following, not some of them:

• ILMT deployed within 90 days of the first eligible deployment, or an approved equivalent such as Flexera One ITAM or HCL BigFix Inventory.
• Running continuously, with agents reporting against every host where the software lives.
• Quarterly reports generated and retained for two years.
• Eligible virtualization, since ineligible technology voids the claim regardless of the tool.

Fail any one of these for a period and IBM defaults that period to full capacity charging. The conditions are joined by AND, not OR, which is the heart of the trap.

How the trap springs in an audit

It rarely springs because someone ignored ILMT. It springs because an agent quietly stopped reporting, a new cluster was never added, the quarterly reports were not kept, or VPC metered products moved under sub capacity reporting after Passport Advantage v11 and the process did not follow. Each gap is small. The charge is not, because the lookback can run 2 to 5 years at full capacity rates.

Closing the trap before an auditor finds it

The defensible posture is provable, not assumed. That means agents reporting on every eligible host, quarterly reports archived, and the configuration corrected for the installs ILMT miscategorizes by default. Validate it on your own schedule and the sub capacity claim holds when IBM tests it, which is the difference between 480 PVU and 3,840 PVU on every host in scope.