IBM is a leading expert with partitioning and server virtualization technologies. They recognize non-IBM technology also, like VMWare, as a way to meet the demand for flexibility. They introduced subcapacity licensing in 2005 as a tool to assist customers in maintaining compliance in a dynamic environment.
Subcapacity for IBM software with PVU (core-based) licensing metrics is desirable because only the capacity used needs licensing. This would work well for partitioned, virtualized, dynamically allocated, or even cloud-based environments.
The default for IBM software licensing is full capacity. That’s licensing for every activated, physical processor core on the server(s) where the software is deployed. Clustering would dramatically increase the software licensing burden with full capacity.
The condition for sub-capacity licensing from IBM is utilization of one of their tools, such as ILMT or TAD, and retaining a minimum of quarterly reports for two years. Some clients have asked for an exception based on using a non-IBM comparable tool and have received subcapacity entitlement from IBM.
Why does this matter?
If you have a couple 4-core max partitions of WAS on a Power 6 with 64 cores with full capacity, all 64 cores would be used to calculate the PVU licenses in a full capacity scenario – 64 x 120=7,680 PVUs.
With sub-capacity, only 8 cores would be counted for licensing – 8 x 120 =960 PVUs.
How much is that in terms of list price?
Full Capacity = $400,000 for 7,680 PVUs.
Sub Capacity = $50,000 for 960 PVUs.
IBM WebSphere Application Server Processor Value Unit (PVU) License + SW Subscription & Support 12 Months (D55W8LL) is $52.25 list price on IBM’s web site Oct. 11, 2013.