VSI now owns and supports PERFDAT, the most comprehensive data collector and analysis tool available.

PERFDAT is an integrated performance monitoring, analysis, and capacity planning solution for OpenVMS Alpha and OpenVMS Itanium. It is designed and developed for monitoring large complex OpenVMS environments and includes comprehensive data gathering, storage, and analysis functions. It also has the ability to monitor the performance of non-OpenVMS systems through standards-based extensions.

more info :

http://vmssoftware.com/docs/PERFDAT/PerfDat%20Release_Final_BRC_TH.pdf