We all know about system determined blksize and there have been rules of thumb for decades about the correct/optimal blksize to use for each type of PDS.
My question is what is the optimal blksize for a PDS based on the member sizes? Having a large a blksize with many small members results in many blocks with wasted space. Having a small blksize with many large members results in unnecessary I/O to read all the blocks of data. The various tools available to provide a best estimate at optimal blksize (e.g. trkcalc, blkdisk, blk3390) and even SDB all provide a best estimate without having any awareness of the planned, or existing, contents of the PDS. Which is better - a BLKSIZE of 3120 with 100 members ranging from 3 to 30 records or that same set of records in a PDS with BLKSIZE of 27920. And similarly what about a PDS with BLKSIZE of 3120 and 100 members ranging from 300 to 9000 records compared to the same set of records in a PDS with a BLKSIZE of 27920. I imagine this will be an interesting discussion. ------------------------------------------------------ Lionel B. Dyck <>< BMC Software Product Development Architect, Common Install and Services 10431 Morado Circle, Building 5, Austin, Texas 78759 Office Phone: 512-340-6031 (extension x26031) Cell Phone: 512-739-3274 E-Mail: lionel_d...@bmc.com "Worry more about your character than your reputation. Character is what you are, reputation merely what others think you are." - John Wooden ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
