Re: HP shared memory limits

Well, since I started this let me jump in here... For a single instance of the Informix engine, you want to avoid allocating more than the initial virtual segment (the engine comes up with three segments, Resident and Virtual which are big and very active, and a "message" segment that is very small and presumably not that active. For Current HP PA-RISC hardware and 10.xx HP-UX versions, 2 segments is the most you can tolerate with a high rate of change between at the instruction by instruction level (within a dispatcher time quantum...). Add another virtual segment, and viola', you have three very active segements. Not good. Add another, and things get worse. And so on. Moral of the story - don't add virtual segments. Period. This is all well known stuff. With HP-UX 11 and PA8200 or up hardware, by the way, I gather that "magic number" goes from 2 to 6, in fairness to HP. What I wanted to know, is for MORE THAN ONE system on the same box/OS - how many instances, each consuming 1.75GB virtual shared storage apiece can I get away with architecturally (10.2x only...)??? Actually, my real question is: Is this number greater than one?? Hint: I suspect the answer is "No, not without patches that won't be available until Mayish that implement Memory Windows...", but I'd like verification from someone who has actually tried it. Thanks - greg David Weis wrote: > > > David Weis <dweis@louisville-i-market.com> offerred: > > :Okay, David. I might agree with you, but I would want to try it first. > > :Just remember that HP-UX 10.20 does not like to have more than two (2) > > :Informix virtual shared memory segments, remember? More than two (2), > > :and they get paged out. HP-UX problem, right? > > > > David Kosenko wrote: > > I believe that was more than 3 segments and they got swapped out. We always > > shot to tune the virtual seg size large enough so that additional virtual > > segments were never allocated under HP/UX. Since you commonly have a shared > > memory message segment along with the resident and virtual portion, 3 was the > > magic number. > > > > Dave > > Oh. So, to interpret for everyone else you are saying the limit on the > shared Virtual portion is one (1) segment. > > See, I remembered (my memory must have been paged out and unaccessible) > it as two (2) Virtual shared memory segments. Well, I think I would > take the easy road out and just set SHMADD to zero (0) and SHMVIRTSIZE > to a LOT. > > Sheeesh!!! My memory is getting overloaded. I think it's time for a > core dump.... > > -- > Thank goodness for bookmarks --- how else could I remember my web site > address??? snip....