Not so sure about making VSAM CI sizes larger unless they are < 4K. SMB sequential buffering should read multiple tracks at a time, so a small CI size is almost irrelevant. Using a large CI size for random is not usually good unless you get several hits in the same CI very close together. SMB will typically activate LSR if pure random access is set, and will do a good job of caching the index and may cache a useful amount of the data. If SMB finds mixed mode (e.g. COBOL DYNAMIC), it will typically set NSR which will bias towards sequential - often not clever. This does depend on how you have set SMB ACCBIAS up of course. I used the generic setting (SYSTEM) and tweaked as necessary on the basis of having some VSAM buffering is better than none given many people's painfully bad attempts at setting up VSAM files. CI splits are almost invisible now in terms of overhead, CA splits aren't, but may be impossible to avoid at all e.g. all inserts at EOF, or without using high CA FSPC % and this wastes space and can reduce sequential performance. VSAM compression adds cpu time, so you may want to avoid that as a general setting.
I agree with whoever said that you need to target the worst cases, but you need smart monitoring for that, e.g. SMF record analysis for VSAM. Have you analysed the scheduling, is there more scope for parallel activity or is there contention that needs eliminating? It may be that you need to make application changes, in some cases people have archived some of the data to reduce processing overhead. I never found the silver bullet myself, and the Batch Tuning Fairy seems to have gone on an extended holiday. I am sorry, but you are probably got a job on your hands. ------------------------------------------------------------------------------------------------------------------ Mike Poil Java z/OS Level 3 Service IBM United Kingdom Limited, Hursley Park, Winchester SO21 2JN Internal: 246824 External: +44 (0)1962 816824 Java debugging: http://www.ibm.com/developerworks/java/jdk/diagnosis/ ------------------------------------------------------------------------------------------------------------------ Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
