ISC limits the amount of cache used for each catalog, and ISC is a "dumb" cache when compared to VLF.
When a catalog using ISC is shared with multiple systems and the Catalog Address Space (CAS) detects an update from another system, CAS will invalidate all the records in ISC. When a catalog using VLF is shared with multiple systems and CAS detects an update from another system, only the records updated will get invalidated, and the rest of the records for that catalog will remain in VLF. All of my catalogs are using VLF. I used to exclude the master catalogs, but there were enough times when an update from another system would cause all of the records the master catalog to get flushed out of ISC. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Jon Brock Sent: Monday, March 26, 2007 1:32 PM To: IBM-MAIN@BAMA.UA.EDU Subject: VLF vs ISC for catalogs As part of a drive to increase catalog performance, I am thinking of moving a couple of our catalogs from ISC to VLF caching. A limited test I have done seems to show that it would help, but I am interested in hearing whether you folks out there (or as we say around here, "y'all") use VLF or ISC for your hard-hit catalogs. Thanks, Jon ---------------------------------------------------------------------- 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
