IBM Mainframe Discussion List <IBM-MAIN@BAMA.UA.EDU> wrote on 07/26/2005 05:39:19 AM:
> On Mon, 25 Jul 2005 23:53:30 -0700, Greg Dyck <[EMAIL PROTECTED]> wrote: > > >> PAV will give you up to eight SSCHs/RSCHs at a time per page data set. > > > >Wrong. ASM will start at most 2 I/Os to a page data set when WLM managed > >PAVs are in use. Otherwise it is a single I/O even if the device has 15 > >alias's assigned. > >Greg > > > > Greg, > > What are the conditions that allow or restrict two Channel programs > running? That's all ASM is prepared to deal with. The z/OS 1.3 ASM PAV support added a second set of I/O control blocks for each page data set. When a single page read (e.g. a page fault) is presented to ASM, if there is already an active channel program to the data set, ASM uses the second set of control blocks to start the read on a PAV, so that the page fault does not need to wait for completion of a long channel program built by swap or steal processing. 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
