On Thu, Apr 8, 2010 at 2:51 AM, Schuh, Richard <[email protected]> wrote: > The 5.3 documentation seems to indicate that the only DPA that counts is that > below 2G. Is that right or has the documentation simply not been brought up > to date? If it is true, it would appear to make the default SYSLIM based on > the Q FRAMES response 513876 / (4 * 2050) or 62.667 GB, assuming that I have > picked the right number for the DPA. It is a whole 'nother ball game if all > DPA is to be considered. > > > The second qualification, as stated below, is not well stated. For example, > defined how? Perhaps the DASD space allocated as PAGE, something that might > not be constant from one ipl to another? That is the only definition that > comes to my mind. How does one have paging space defined that is not "for CP > use"? The qualification seems to imply that it is possible. >
It sounds like the default was based on an earlier implementation that required all PGMBK stuff to reside under the bar, while the contents of the VDISK is subject to paging. And to avoid too much pressure on storage, someone decided it should not take more than 25% of the resources for VDISK. Only reluctantly, I quote Bit, saying "With Linux, it Depends Even More" :-) We're not talking about CMS users looking for 1 MB of temporary space for "big" files... Most installations today define many large VDISKs for Linux swap that don't get used in general. So limits on the size are either too restrictive or not effective at all. I would rather set up alerts that look at performance metrics and determine the real *used* resources rather than "allocated" resources. This is what overcomitting is about... The USERLIM can protect against an uncontrolled Linux sysadmin (or penetrated virtual server). But the consequence is that you must allocate the VDISK in the directory to override the user limit. If it were up to me, I would probably take the DEFINE command away from those Linux servers. But the "Less than Class G" is an entirely different art. The "page space not for CP use" might very well refer to when page volumes are drained. After all, this arithmetic is not just during IPL, but also later if you want. I just discovered the "default" operand of both the SET VDISK and QUERY VDISK commands. Neat. Thank you, Endicott. Rob
