Informix/Solaris Kernel Parameter (semsys:seminfo_semmni)

Hello All, We are running Informix 7.31 on a Sun Solaris 8 server. This week we moved our production Informix server to a different Sun Solaris 9 server. We noticed that 2 of the Kernel parameters were set differently. Old Server - Solaris 8 semsys:seminfo_semmni=100 shmsys:shminfo_shmmin=1 New Server - Solaris 9 semsys:seminfo_semmni=4096 shmsys:shminfo_shmmin=100 I checked the release notes for 7.31 and the recommendations are the way we had it configured on the old Server. What do these 2 (semsys:seminfo_semmni, shmsys:shminfo_shmmin) kernel parameters do or what are they related to?? Also, our production environment is running very well on the new system. Only 2 items we noticed different are checkpoints are taking between 3 and 6 seconds longer and there are between 50,000 and 200,000 more latch request waits per hour (lchwaits from onstat -p). Any help or info on those parameters would be greatly appreciated. Thank You, Dave In4MixDBA@gmail.com

> > What do these 2 (semsys:seminfo_semmni, shmsys:shminfo_shmmin) kernel > parameters do or what are they related to?? > seminfo_semmni on solaris is the maxium number of semaphore identifiers for the system. shminfo_shmmin is the minimum size of a shared memory segment, in bytes.

On 23 Feb 2007 07:53:01 -0800, Dave <In4MixDBA@gmail.com> wrote: > We are running Informix 7.31 on a Sun Solaris 8 server. This week we > moved our production Informix server to a different Sun Solaris 9 > server. We noticed that 2 of the Kernel parameters were set > differently. > > Old Server - Solaris 8 > semsys:seminfo_semmni=100 > shmsys:shminfo_shmmin=1 > > New Server - Solaris 9 > semsys:seminfo_semmni=4096 > shmsys:shminfo_shmmin=100 > > I checked the release notes for 7.31 and the recommendations are the > way we had it configured on the old Server. > > What do these 2 (semsys:seminfo_semmni, shmsys:shminfo_shmmin) kernel > parameters do or what are they related to?? > > Also, our production environment is running very well on the new > system. Only 2 items we noticed different are checkpoints are taking > between 3 and 6 seconds longer and there are between 50,000 and > 200,000 more latch request waits per hour (lchwaits from onstat -p). As J P Renaut said: > seminfo_semmni on solaris is the maximum number of semaphore > identifiers for the system. > shminfo_shmmin is the minimum size of a shared memory segment, > in bytes. The values mentioned in the release notes are suggestions, not commandments. Being able to have more semaphore sets won't cause problems for IDS; I suppose it might waste a little system resource, but you're unlikely to be able to measure it. The minimum size of a shared memory segment is more intriguing. IDS won't be using small size shared memory segments - not in the sub-kilobyte range - but some other parts of Solaris do. In particular, I seem to remember the powerd (power daemon) using 16 or 20 bytes in Solaris 7, but just 4 bytes in Solaris 8. So, I had shmmin set to 4 - but 1 is a perfectly reasonably alternative, quite honestly. You won't see a problem with large values of shmmin unless you monitor your boot logs (/var/adm/messages, IIRC). -- Jonathan Leffler #include <disclaimer.h> Email: jleffler@earthlink.net, jleffler@us.ibm.com Guardian of DBD::Informix v2005.02 -- http://dbi.perl.org/ NB: Please do not use this email for correspondence - I don't read it every week, even.