Previously, I have used Performance Essential and when it was implemented it saved huge amounts of time, as it changed what the default vsam buffering mode of NSR and activated LSR. In a prior job, we saved around 10 million i/o's per week for just one application.
The products like Performance Essential all will provide a great performance boost, if you currently do not have any form of vsam/qsam buffering tool (i.e. you may be coding BUFND and/or BUFNI). IAM works differently than the tools such as BMC's Batch Optimizer, Performance Essential, etc. IAM does not do buffering changes of the vsam datasets, like Batch Opt/Performance Essential. Instead it becomes kind of the "media manager" (if I may use that term loosely). A file gets defined and marked (via OWNER in define or via SMS construct) as an IAM dataset, and then IAM allocates the physical space as a DSORG PS dataset. When the system goes to open it, IAM does all the file I/O and loads the entire index into memory. With how IAM does things, it can also provide performance improvements above and beyond what Batch Optimizer/Performance Essential/etc. provide. Peter ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
