Re: On Informix Virtual Segments - SHMADD/SHMVIRTSIZE

Hi, hmm, I guess you now have to also look at the output of system command "ipcs -m", execute that as user root. This will tell you, how many SHM segments there are on the OS level. And this is the relevant info for the OS limits. [ If IDS requests from the OS an SHM segment that is bigger than the OS limit on the size of an individual SHM segment, then the OS will first deny it to IDS. IDS will then go and request SHM segments of smaller size. You will see these on the OS level ("ipcs -m"), but since IDS will map them into the address space consecutively, it can then pretend that it would be one big SHM segment. Hence "onstat -g seg" will show that whole stuff as one segment ... ] Now with the 2 segments seen in your "onstat -g seg" you are already pretty much at the limit anyway, these (almost) 2 GB. You can try to optimize a bit further, but it probably will not help a lot. With that much physical memory in the box, have you considered "upgrading" to a 64-bit IDS ? Regards, Martin -- Martin Fuerderer IBM Informix Development Munich, Germany Information Management owner-informix-list@iiug.org wrote on 15.02.2005 22:02:06: > > I am not doing shared memory connections. > Below is the output for onstat -g seg > > > Informix Dynamic Server Version 7.31.UD7 -- On-Line -- Up 14 days > 14:09:36 -- 1944016 Kbytes > > Segment Summary: > id key addr size ovhd class blkused blkfree > 19136525 1381451777 30000000 864272384 32928 R 105497 5 > 14811156 1381451778 70000000 1126400000 17832 V 108881 28619 > Total: - - 1990672384 - - 214378 28624 > > (* segment locked in memory) > > > Thanks! > > > > > "Madison Pruet" > <mpruet@comcast.n > et> To > Sent by: informix-list@iiug.org > owner-informix-li cc > st@iiug.org > Subject > Re: On Informix Virtual Segments - > 02/15/2005 02:37 SHMADD/SHMVIRTSIZE > PM > > > Please respond to > "Madison Pruet" > <mpruet@comcast.n > et> > > > > > > > Are you using the shared memory interface to connect to the engine? If so > then the message buffers count against the limit of 10. So if you ran into > trouble after 2 segments were added, then I suspect that you might be > running with 6 message buffer segments. That would be 6 message buffer > segments, 1 buffer pool segment, 1 initial virtural segment, and 2 > extension > segments. > > Post the output of onstat -g seg so we can check to see if that is the > case. > > M.P. > <jpierrot@chubb.com> wrote in message > news:1108494664.6cafd5ec1dd1c5ae0967ee6580fa4425@teranews... > > > > > > > > Can anyone help shedding some light on the following issue. Informix IBM > > tech is saying one thing while IBM AIX tech contradicts its counterpart. > > I have one IDS instance on AIX 5.2 and the Informix ver is 7.31.UD7 , > > 32bit > > SHMVIRTSISE set to 1100000 > > SHMADD set to 100000 > > BUFFERS set to 200000 > > SHMTOTAL set to 0> > Physical Memory of Box is 8GB > > The total instance size is about 2GB or 1.94GB (1944016) > > One day the instance try to add segments to support the workload. It > added > > one successfully and about 1 hour later it hung and finally went down > > while trying to add another segment with the following MSG. > > > > shmat: [EMFILE][24]: out of shared memory segments, check system SHMSEG > > shmdt: errno = 22 > > From talking to Informix I gathered the following info : > > > > AIX has OS limitations which are not tunable on most versions. > > (dynamically manage by OS) > > It allows 10 segments per process (SHMSEG 10) and the maximum size > > for a segment is 2 gigs. Consider checking with AIX tech support, to > see > > if there are any > > OS patches which can help overcome this obstacle. > > Note : The keyword here is: a segment > > My segment was still under the two gigs limitation and also I tested > and > > were only able to dynamically add 2 segments on a test box under the same > > configuration. I ended up with the same scenario. But after setting the > > environment variable : > > EXTSHM > > I was able to add one more to a number of 3 segments > > *** > > But IBM AIX tech support stated : > > 2 gigs is the architectural limit for a 32 bit O/S. > > > > Does that translate to a 2gigs limitation per process and your > instance > > total memory size cannot grow beyond 2 gigs in a 32 bit platform > > If the above doesn't hold true, is there a workaround to this issue? > > Are there any shared memory parameters in AIX that can be tuned to > > address the problem > > Is 64bit the only solution. (I am not trying to go that route yet > till > > next year IDS9.x migration, but our platform is 32/64bit) > > > > Your insights would be greatly appreciated. Thanks in advance. > > > > Josue' > > > > > > sending to informix-list > > > > > > sending to informix-list sending to informix-list