Re: IBM AIX Kernel parameter limitations

We are using the AIX Platform from C10 up to 12 (SMP) node MPP SP2's and we are making extremly well. We are therefore currently very happy with this platform. The shared memory limit of 10 segments only exists for a single process So in the whole there can be a lot more shared memory segments A typical ipcs -mb: ilrza01i:informix> ipcs -mb IPC status from /dev/mem as of Fri Nov 14 11:30:54 1997 T ID KEY MODE OWNER GROUP SEGSZ Shared Memory: m 4096 0x67070879 --rw-r--r-- root system 12 m 1 0x444d4132 --rw------- root system 667648 m 2 0x444d4133 --rw------- root system 663552 m 3 0x68070879 --rw-r--r-- root system 26676 m 4 0x0d064045 --rw-rw-rw- root system 1440 m 4101 00000000 --rw------- root system 52428800 m 6 0x78050422 --rw-rw-rw- root system 16777216 m 7 0x78070844 --rw-rw-rw- root system 7152 m 24584 0x52564801 --rw-rw---- root informix 268435456 m 24585 0x52564802 --rw-rw---- root informix 268435456 m 24586 0x52564803 --rw-rw---- root informix 5906432 m 24587 0x52564804 --rw-rw---- root informix 134217728 m 81932 00000000 --rw------- root system 40960 m 20493 0x52564805 --rw-rw-rw- root informix 712704 m 8206 00000000 --rw------- root system 52428800 m 94223 0x780506a4 --rw-rw-rw- root system 2256 m 16400 00000000 --rw------- root system 40960 m 16401 00000000 --rw------- root system 40960 m 4114 00000000 --rw------- root system 40960 m 12307 0x52564806 --rw-rw---- root informix 67108864 There is no need for Kernel tuning except: max processes per user 256 (no tuning effect) max MBUFS 16384 and aio (increase max proc to be >= cpu VP's) we also tuned the network stuff (try command: no -a) Andreas Zeugswetter Spardat~Austria Greg Moye wrote: > > Oh, I'm not so sure. For perfectly good reasons you may want multiple > database instances on the same machine, or have an application (like > SAP) that requires some shared segments as well. Each Informix > instance requires at least 3. Not sure yet about SAP, but at least a > few per system appear to be unavoidable. Machines with the > aforementioned "screwy shared memory problems" are a major pain in the > backside in our environment. I doubt we're the only ones who find this > unacceptable, given that there are perfectly good alternatives. > > Greg > > Mark D. Stock wrote: > > > > Greg Moye wrote: > > > > > > Gee, you guys have a talent for picking machines with screwy shared > > > memory problems. I've read (no direct experience) that AIX/RS6K > > > machines have a hard limit of 10 shared memory segments. That's all. > > > Want more? Buy another box. > > > > But let's face it. If you're allocating ten segments, you have a poorly > > tuned system. :-) > > > > Cheers, > > -- > > Mark.