SMF DIRECTOR 12.6 added a SUBSTREAM facility that permits segregating SMF types/subtypes into their own separate SUBSTREAM/HISTORY files, maintained apart from the SMFD-generated standard HISTORY file content. This feature stands to help make available designated SMF data more quickly than needing to recall/retrieve the standard SMFD tape/DASD HISTORY files. At one site I support, the DB2 SMF 101 data represents upwards of 70% of the total SMF data generated (in bytes), with CICS 110 and MQSeries 116 between 10 and 20% - so by creating separate SUBSTREAM definitions for these SMF types, nearly 80% of all SMF data is kept separate for those more popular SMF types/subtypes which may be needed for SMF data-extract or retrieval/analysis purposes. The feature is easily implemented and can be activated for an individual LPAR, possibly for testing purposes. And it can be tested using a separate SCDS definition along with already-dumped SMF data, using an SMFD SOURCE/DUMP override batch-execution technique. Unfortunately, there is not much information in the SMF DIRECTOR USER manual about SUBSTREAM implementation -- I have asked CA to help make users aware by increasing awareness with more examples and implementation discussion for SUBSTREAM. SMF DIRECTOR sites should seriously consider this feature, in addition to the SPLIT feature for creating duplicate-copy SMF data, generated by SMF DIRECTOR. Scott Barry SBBWorks, Inc.