CR+ and its VSAM Mgr component Bob
-----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Ward, Mike S Sent: Thursday, March 12, 2009 5:09 PM To: IBM-MAIN@bama.ua.edu Subject: Re: VSAM files Thanks for the tip(s). -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Tom Harper Sent: Thursday, March 12, 2009 4:06 PM To: IBM-MAIN@bama.ua.edu Subject: Re: VSAM files Mike, Such tools exist (I think McKinney Systems has one), but I don't think you would want to use it in the manner you have described. Here's why: * CI/CA splits are not indicative of poor performance. If you reorg such a file, the splits are likely to re-occur. * Total extents do not degrade performance on today's RAID devices. * EXCPs are not recorded for many types of VSAM I/O, for example, Media Manager and STARTIO. * Statistics kept in the VSAM catalog are stale and only updated when the file is properly closed, perhaps never. I would study up on VSAM performance (there are some good sessions at SHARE) and re-assess your criteria. Then, be thankful you only have hundreds of VSAM files. I know of customers who have over a million VSAM files. In general, VSAM performance problems are less related to the data sets themselves and more related to the techniques used to access them, buffers, LSR, etc. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
