In any case, so not only paging: the model you'd use depends on the IO rate. If you need lots of space with low IO rates: bigger models don't penalize you. PAV will lower the observed IO rate.
CP's paging routines don't exploit PAV. So, if you'd have lots of stuff slowly paged out and in, a model 27 would work well for paging too. By default though I'd recommend the smallest possible model for paging. Side info: DB2/VM nor SFS can much benefit from PAV: they know where their minidisks are located and won't attempt to launch a new IO when they have an IO active one on a given pack. If minidisks of other users are located on a pack used by SFS/DB2, then CP may use PAV to launch a extra IOs while SFS/DB2 have an active IO. With other words: - when a pack is given to one DB2/SFS server, with fullpack mdisks or multiple mdisks: PAV won't be used - when a pack is shared by multiple users (DBD, SFS, normal CMS), PAV can help. When DB2/SFS use dataspaces, CP's paging routines perform the IO, hence no PAV either. 2009/4/1 Scott Rohling <scott.rohl...@gmail.com> > If you have to pick a model - I would go with the 3390-3.. best for > paging, etc. > > My current customer is using mod9's with PAV -- no issues, although I think > their paging performance would be better with mod3's for paging volumes. > > 3390-27 I would reserve for guests (such as Linux) which can use that much > space all at once - or for CMS guest minidisks. I doubt there is any > problem using them for the z/VM system volumes, but I definitely would not > use them for paging. > > Others can probably speak with more technical detail about what's preferred > and why.. > > Scott > > > On Tue, Mar 31, 2009 at 4:29 PM, <sunny...@wcb.ab.ca> wrote: > >> >> I plan to install z/VM5.4. We has 3390 model 3; mod 9 and mod 27. And we >> use Z10. >> My question is which one is better for VM CP module and paging space? >> VM5.4 CP palnning and Administration said "3390 model 9 is not recommended >> for CP system areas and does not support track"---on "Allocating Dasd Space" >> And another book said 3390-3 are preferred for page. >> >> So does that mean model 3 is the best solution? What about mod 9 if we has >> PAV? >> Can we use mod27? Any problems? >> >> Thanks >> >> >> >> ------------------------------ >> This message is intended only for the addressee. It may contain privileged >> or confidential information. Any unauthorized disclosure is strictly >> prohibited. If you have received this message in error, please notify us >> immediately so that we may correct our internal records. Please then delete >> the original email. Thank you. (Sent by Webgate1) >> > > -- Kris Buelens, IBM Belgium, VM customer support
