On Wed, 28 Jan 2009 21:10:10 +0000, Ted MacNEIL <eamacn...@yahoo.ca> wrote:
>>I almost horked my coffee. Following this thread from the beginning, I've been thinking, "Gee... I guess we're not most shops!" > >The main issue with the ENQ Reservation Value is that the default is WAY too >small. Yes, I agree. > >The second issue is what to set it to. Yes. > >When I got involved with RACF ENQ problems, we were told to set it it to 200000. > >The only problem with that, is no problem. >If 200K is not enough, you have a big problem. >If 200K is too much, it doesn't matter because the task doesn't consume the rest. >It's a ceiling, not a minimum. > Sort of. It is a ceiling that could be hit over and over and over again. It is a minimum time the DP will be promoted. (I dropped this thread before because I really have no hard evidence to back up what I am about to write, nor are there any white papers etc. that I know of, nor any definitive recommendations from SHARE presentations that I can find.) Even some quoted IBM resources had different values (10K, 50K and 200K from you are all numbers I've heard so far). It is the time the ENQ will be promoted. If you have a shop that routinely submits lots of jobs that get initiated and remain in ENQ contention, (say, everyone and their uncle wants SMF data from tape) too high of a value is going to cause extra CPU cycles to be wasted. You're going to promote the DP for all those ENQ holders for no reason at all for a longer period of time. Also, I think with blocked workload support, the exact setting is less important than it was before. But not everything takes advantage of that support. I'm not a capacity / performance analyst by current job function and I don't attend / follow CMG. Perhaps someone who does can say what has been discussed at CMG about this. Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group - ZFUS G-ITO mailto:mark.zel...@zurichna.com 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 lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
