On Thursday, 08/17/2006 at 09:39 EST, Brian Nielsen <[EMAIL PROTECTED]> wrote: > >It certainly affects the size of the HSA *IF* that particular IOCDS is > >marked to allow dynamic updates. If you don't specify MAXDEV=, it > >defaults to the maximum number of devices allowed by the processor. That > >means your HSA will be as large as it can possibly be. > > Does that mean that for a dynamic IOCDS I can change the size of the HSA > by means of the MAXDEV parameter? For example, if I have only have 4K > devices can I lower MAXDEV from 63K to 20K and thus recover some memory > from HSA and still leave lots of room for dynamic I/O changes?
>From my understanding of how the IOCDS and the HSA interact, yes. Also remember that a "device" isn't a physical thing, it's a logical construct in the IOCDS. A single physical device (e.g. dasd volume) that is visible in 6 LPARs uses 6 devices in the IOCDS. Add in spanned channels and logical channel subsystems for more fun and games. There is an HSA size estimator on ResourceLink. Look under "Tools". Alan Altmark z/VM Development IBM Endicott
