On May 1, 2012, at 6:39 AM, Andrew Rowley <[email protected]> wrote: > 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
Basically it is to do with the fact that WLM works best with a limited number of total service class periods and it is better not to "waste" them on multi-period classes. That total number seems to vary according to which direction the wind is blowing, but given the sysplex-first nature of the algorithms it makes good sense to keep it small. The second reason is that the algorithms only work well when you have sufficient completions for a statistically valid sample. It is very likely that multi-period classes (other than perhaps TSO) would not have enough and so they might/would not be treated appropriately. The take-away from that is that WLM is a statistical tool and trying to get very fine-grained with it will likely end in tears. CC ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
