IBM Mainframe Discussion List <IBM-MAIN@BAMA.UA.EDU> wrote on 07/28/2005 09:20:17 AM:
> Bill, > > Thanks for taking the time to write this response. It is most informative. > This goes straight to my useful information folder. > > So, if ASM will treat PLPA and Common as a single Common+PLPA extent than I > will stand corrected. There is benefit to be gained by having them allocated > adjacent to one another. > > It would be good to know if there is any other logic applied for ASM to do > this. For example must the order of the datasets always be PLPA and then > Common? Does this operate for a PLPA larger than one Cylinder? > > I am also wondering if this continues to operate in this way for PAV. With > PAV I would think that a page-in from the PLPA dataset would use one of the > UCB assigned to PLPA, rendering the need for adjacent datasets redundant. > > With PAV I would suggest that a dedicated PLPA and Common Dataset (i.e. no > overflow) on the same volume would provide almost the same throughput as two > dedicated volumes - whether or no they are adjacent. I have never heard of ASM treating a contiguous Common+PLPA as a single extent, nor have I seen any code in ASM to do this. If there were such a function, I would think there would be some code to deal with it in ILRASRIM, but I don't see any. ILRASRIM (and most of ASM, I think) remains non-OCO, for those who wish to investigate further using VPL or old microfiche. I anyone finds documentation or code for this function, I would be interested in hearing about it. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- 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
