On Wed, 2 Aug 2006 16:35:56 +0200, Vernooy, C.P. - SPLXM <[EMAIL PROTECTED]> wrote:
>I was wondering if and why CTConly is faster than Dasdonly. We use Ficon >and ESS and have no I/O queing and 100% cache hit ratio for the control >file. In the Dasdonly configuration each system has to >waitfor-read-writeback the control file, in a CTConly each system, >except the Master, must request-update-sendback the controlfile, in both >cases on Ficon speed. The Master will of course benefit from owning the >VCF, but do the clients benefit substantially from CTC mode? I would think the answer is HARDWARE RESERVE. Hardware reserve is still slow (FSVO of slow). That is why in a GRS STAR (or MIM in CF) configuration, the old ROTs go out the window for what is okay to leave as a reserve. > >With "allowable load" I refer to the MII activity rate that will not >impact performance. I remember we removed SYSIGGV2 from converting to >global enq when the Dasd control file was still on Escon chached disk, >because this amount of activity in MIM was noticable in the system >performance. You're lucky you didn't end up with a deadlock then. SYSIGGV2 should be converted. SYSVVDS / SYSVTOC should not be. If you convert one of them, you must convert both. > >The CA doc seems outdated. It mentions 3088's and Escon but no Ficon and >the reported cycletimes seem rather high to me for current hardware: 6 >msec cycletime for CTC and XCF, our Dasd cycletime is 3 - 4 msec. Maybe >Norman can trigger some updates on this matter? > Contact CA. Cheers, Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group mailto: [EMAIL PROTECTED] z/OS and OS390 expert at http://searchDataCenter.com/ateExperts/ 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
