I have a paper that documents the reaction time of WLM based PAV as opposed to HyperPAV. HyperPAV is instantaneous, in fact the IOSQ time in my test was zero for all intervals. Dynamic PAV controlled through WLM takes four minutes to adjust to a changing workload for a device and never gets the IOSQ to zero. The paper has been accepted for presentation at CMG in December of this year.
Tom Moulder -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Mark Zelden Sent: Friday, September 12, 2008 3:19 PM To: [email protected] Subject: Re: Hyper PAVs vs. Dynamic PAVs On Fri, 12 Sep 2008 19:57:01 +0000, Ted MacNEIL <[EMAIL PROTECTED]> wrote: >>One of the nice things about HyperPAV is that if you share DASD between sysplexes, you don't have to worry about "PAV thrashing" like you would if you had WLM controlled PAVs active to both sysplexes for the same DASD. > >IBM has always admitted, unashamedly, that as of SYSPLEX, DASD sharing is problematic between SYSPLEX'. > >Also, for the exaggerator in the crowd, the maximum WLM interval is 10s, not 10m. >- 10 seconds is the policy adjustment interval. But there are 2 algorithms controlling PAVs IIRC. One is to help goals and that runs about every 30 seconds. The other is for overall system efficiency and that runs about every 60 seconds. The problem is that they don't do much at each interval (each one is slightly different) so adjustments are very slow. Multiple devices can be adjusted, but no more than one alias will be added to a particular device during that cycle. So it can take a long time (maybe even 10 minutes) to get to where you need if there is a sustained increase in IOSQ. A good example would be when your onlines come up in the morning or when everyone walks into the office around the same time and starts doing work. I probably have this close... but not exact (it's been a while since I reviewed this information). It is documented in the Sysprog's Guide to WLM RedBook. 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 ---------------------------------------------------------------------- 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
