On Tue, 1 May 2012 21:39:05 +1000, Andrew Rowley <[email protected]> wrote:
>Hi, > >I have read a few articles that say that multiple periods are not >recommended for batch service classes. Multiple periods seems to be >considered a bit old fashioned. > >I haven't been able to find anything clearly explaining why. I have >always felt that they worked well. My best guess is that it is something >to do with the behaviour of WLM managed initiators but I'm not sure. > >Can anyone shed any light, or point me to some further reading? > I have never had much use for them. I only used them prior to goal mode for a quick turn around / "express" JOBCLASS that maybe had a 10 second CPU time limit. The idea was that if someone submitted a job to that class that was a quick IEBGENER or compile they would get in and out of the system quicker - even when the system was busy. That doesn't really work well with goal mode, since DP isn't "hard coded" like I had it on IEAIPSxx when I did such things. Sure, you could assign that jobclass to a service class who's first period had a high importance and CPU critical - but it's batch! So the reason may be WLM, but not WLM managed initiators. I think the other reason to not use them with goal mode (again, not related to WLM initiators) is the more general one related to trying to keep the total number of active service class periods to no more than 25-30 per system. And of course the less (active) periods WLM has to manage on a given system, the better. Put another way, SC periods are a "precious resource" and you don't want to waste it on a batch workload when perhaps an interactive workload really needs it more. TSO/DDF/OMVS are the only SCs I have with periods. TSO, OMVS and my prod DDF have 2 periods, but my DDF associated with non-prod (QA/TEST) has 3 periods, with the 2nd one being very long and the 3rd being discretionary for some batch like long running enclaves. Regards, Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS mailto:[email protected] Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://expertanswercenter.techtarget.com/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
