On Thu, 18 Sep 2008 09:10:11 -0400, Mark Jacobs <[EMAIL PROTECTED]> wrote:
>Hylton Tom P wrote: >> As DB2 guy, I used to religously use the CSVLLAxx member to avoid >> impacting others. >> >> However, my main zos guru recommended to me a while back (maybe the last >> 2 ZOS releases?) that the benefits were so minimal now that it wasn't >> worth the effort to code the CSVLLA route any longer, and to just go >> ahead and do a total refresh each time. >> > >From a performance standpoint I don't see it as being a big hitter, but >using F LLA,REFRESH always has the possibility of unexpected changed >modules becoming active. Using F LLA,UPDATE=xx at least has the known >effect of only updating the "stuff" in the member. Tom, your main z/OS guru is blowing smoke. Nothing has changed in regards to the processing of LLA/VLF for a very long time as far as I know. I certainly wouldn't do a full refresh it as a matter of habit for either reason (performance or making a change that wasn't expected). The impact certainly depends on the size of your VLF cache since all those objects will be invalidated. If you are running the sample COFVLFxx with only 16M MAXVIRT perhaps the impact isn't worth talking about. But if you 300M of CSVLLA VLF cash with thousands of objects that have to be re-fetched from disk, then there could be a small blip. Would you notice it when you hit enter in TSO? I highly doubt it. But I've worked in environments where if the demand paging rate was anything but 0, CICS transactions backed up and response time when to @#$#. In that type of environment I wouldn't want to do anything that I know would impact performance. I wouldn't want to do something in any environment that I didn't have to do if I knew it could impact performance. YMMV. Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group - ZFUS G-ITO mailto:[EMAIL PROTECTED] z/OS Systems Programming expert at http://expertanswercenter.techtarget.com/ Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html ---------------------------------------------------------------------- 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
