IBM Mainframe Discussion List <[email protected]> wrote on 03/12/2008 02:33:10 PM:
> Note that HYPER-PAVs don't play in the paging subsystem yet. Still awaiting > word on this issue from IBM (Jim Mulder, maybe?). HyperPAV does work with paging the same way as Dynamic PAV, but you still do need to specify WLM PAV for the device in HCD to get ASM to do two concurrent I/Os to a page data set(even though WLM isn't really managing HyperPAV). I nagged the ASM developers about this again recently, and they said they would try to get this fixed in z/OS 1.10. When a paging device is marked as WLM PAV in HCD, ASM creates two sets of I/O control blocks for each page data set. The first set is used any paging I/O. The second set is used to do a single page read to satisy a page fault if the first set is busy (so that page fault resultion doesn't get blocked by a long page-out channel program created by page steal.) For Dynamic PAV, ASM recommends to WLM that there should be 2 PAVs for each page data set on the device (in addition to however many else WLM decides there should be). However, IOS knows nothing of this, so those PAVs aren't really reserved for ASM use. IOS will happily use them to start any request to that base device if the need arises. With HyperPAV, there is a pool of PAVs for the control unit, and IOS selects a PAV from the pool for each I/O operation. The PAV is bound to the base device only for the duration of that I/O operation, and then goes back to the pool so that it can subsequently be selected to be used for another operation to another base device. 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
