On Wed, 7 May 2008 14:58:21 -0500, Staller, Allan <[EMAIL PROTECTED]> wrote:
>It depends. > >In the old SLED days this could be performance crippling, especially if >there was a decent paging rate(remember only one actuator/volume). With >little or no paging this would not be a large problem. > >Fast forward 20 years: > >Data is mapped transparently to many many small drives, accessed by many >actuators. Again if there is no significant paging, no problem. If >significant paging occurs, this MAY BE a problem, maybe not. > >Having said all of the above, my distinct preference would be for one >page ds the size of the 3 currently occupying the volume. > >HTH, > > ><snip> >I noticed again today that we have 6 local page datasets on 2 volumes - >each a 3390-3. I'm sure they have Pavs, or the equivelent on the dasd, >but I'm just wondering if that is a good practice or not. ></snip> > > >---------------------------------------------------------------------- >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 It is best to have a minimum of four(4) local page datasets; more is better. The heavy hitter that gets lost in the mix is an SVC dump. This can put quite a load on the paging configuration when it needs to page-in a lot of inactive frames, just to write them out to a dump dataset. The system will be disabled while the copy process copies this to a dataspace (which, in turn, can stress the real storage configuration, and thus cause more page-out activity). You really want to be disabled for as short a time as possible. So, more concurrent paging I/Os is better; the way to get that is more local datasets. With PAVs, they need not be on different volumes. Without PAVs, separate volumes are strongly recommended. ---------------------------------------------------------------------- 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
