On Fri, 15 Dec 2006 15:30:38 +0100, Pohlen (Mailinglist) <[EMAIL PROTECTED]> wrote:
>Kris, > >I have now figured out from the IND SPACE every minute that the SQLDS us er >has only DASD paging between 300 and 700 pages per second in spaceid >MAP0000000000. The BASE spaceid has no paging. Because Xstore is not def ined >there is obviously no xstore paging. Would it make sense to define Xstor e? >I'm not sure if a CMS user uses it. > >Franz Josef > The paradigm is different on a FLEX-ES system than on a conventional IBM mainframe with respect to xstore. Whereas paging to xstore may have been faster than I/O to disk could have been accomplished on the old mainframe, on a FLEX-ES system using interna l dasd, with a cache hit we can satisfy an I/O from control unit cache in micro seconds under ideal conditions. The path length for xstore is longe r. The "Oooooh, xstore is faster" paradigm does not fit well at all in the FLEX-ES world. I do not generally recommend xstore in a VM environment, other than a tok en amount due to an idiosyncracy of the CP paging algorithms in VM that may function slightly better with a token amount available. And I never recommend MDC to xstore on a FLEX-ES system in light of the speed that I/ O can be satisfied from controller cache. Ed Zell asked some excellent and pertinent questions in his post for whic h I did not see an answer posted. -- Gary Eheman Fundamental Software, Inc http://www.funsoft.com
