On Mon, 17 May 2010 12:46:42 -0400, David Andrews <[email protected]> wrote:
> >Eileen McClintock has done a presentation at SHARE about catalog tuning. >See if you can find it. She recommended (in 2007), among other things: > > - Shared catalog volumes kill you. Don't have > multiple catalogs on the same volume. Don't have > catalogs on shared volumes, period. In the latter > case every catalog lookup requires a VVR read, > regardless of whether the entry has been cached. > I think you are referring to VVDS mode sharing. If you have the catalog in ECS mode, the above isn't true. As an aside, it's a little difficult to avoid sharing catalogs between systems these days. :-) I would also add to use VLF instead of ISC for any catalogs that are shared (make sure the catalog is defined in COFVLFxx on ALL sharing systems). With CDSC, only changed records are invalidated from the cache. With ISC, or a mixture, if any sharing system does an update, the entire cache is purged. Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS mailto:[email protected] Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html Systems Programming expert at http://expertanswercenter.techtarget.com/ ---------------------------------------------------------------------- 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
