On Thu, 20 Dec 2007 08:54:51 +0100, Vernooy, C.P. - SPLXM <[EMAIL PROTECTED]> wrote:
>> >> Yes - of course with a shared CF engine. But with current hardware >(link >> technology, z9 engines) the links are once again faster. YMMV. >> >> Mark > >I was at a Parallel Sysplex and Performance training earlier this month >and the teacher told us, that CTCs ourperform CF signalling paths, >because of the multiple step (write, notify, read) approach for the CF >path versus the single step (what is written is synchronously read at >the other side) approach for the CTC path. And as I said: if the CTCs >for our production sysplex are going to perform as they do now in our >testsysplex, and I so no reason why not, then they will double the XCF >signalling performance. > Ahhh... a teacher at a class told you. Then it must be true! :-) I understand that (this is the way I heard it explained once) "a direct pipe is quicker than a mail box". But there are a lot of factors that go into "YMMV" with this. Type of links, how many, speed of the CF CPs, average message size, rate of signaling, etc. For example, for small messages (1K) even ESCON can be better than FICON at lower signaling rates. Here is a recent post from Barbara Nitz where she talks about this in her installation: http://bama.ua.edu/cgi-bin/wa?A2=ind0712&L=ibm-main&D=1&O=D&F=&S=&P=142096 I haven't looked at our numbers closely since we brought in z9s, but I know that the CTCs aren't getting used... even though they are defined and I have 4 transport classes. You will also find a lot of contrary information to what your teacher told you in this white paper: Parallel Sysplex Performance: XCF Performance Considerations V3.1 http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP100743 The benchmarks in that paper were done with a z990. A z9 CP is much faster, although that is only part of the response time equation. But what really matters for you is the results in your environment using your hardware. So I'm not disagreeing that CTCs are faster for _you_. BTW, can you say what your HW config is (CF, type of links, FICON EX or FICON EX2, etc.)? 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
