SUMMARY : semaphores and oracle instances

From: Jacques Demeulemeester <demeule_at_univ-lille3.fr>
Date: Fri, 13 Oct 1995 17:25:48 EDT

My original message was :
-----------------------------
Hi all
 does anyone know what the upper limit of semaphore number under osf1 (digital
unix)? The documentation gives the default value of the parameters semmni,
semmns, semmsl, but don't give the upper limits, neither how to configure them.
My purpose is to "mount" several oracle databases on the same box (3000-600 with
128 Mo RAM under OSF1 V3.0 347 alpha), and I reach the actual limit of semaphore
number, which is currently 100.
Any help is welcome
JD
------------------------------
I got several responses, giving two ways to get the solution :

1) modify /etc/sysconfigtab and add the entries (if doesn't exist) :

ipc:
   sem-mni = <value>
   sem-mns = <value>
   sem-msl = <value>

and reboot the system.

2)modify /sys/conf/MACHINE_NAME : add or modify the lines

semmsl <value>

and so on and then recompile the kernel with doconfig


For my problem (several oracle instances on the same box), the best information
was given by Georges Dubus <Georges.Dubus_at_univ-lille1.fr (Georges Dubus)>. He
gave me a copy of an ORACLE french support paper, with a discussion of the number
of semaphores needed by several instances on the same box.

If I try to resume the 3 pages of the dicussion, 3 parameters of the kernel add
to be modified, semmsl, semmns and semmni.

semmns = sum of the "processes" parameter of each instance (see
init<instance>.ora for each instance)
semmni = number of instances running simultaneously;
semmsl = semmns

I used the first method (sysconfigtab) to modify the parameters, and that was
good for me (3 instances running together)

Caution : this tuning method doesn't take care of other softwares running also on
the box and using semaphores too.

Many thanks to :

Georges.Dubus_at_univ-lille1.fr
Doug Phelps <Doug_Phelps_at_notes.seagate.com>
Benoit MAILLARD maillard_at_fgt.dec.com
Pedro Ferrer ferrerp_at_inta.es
Hellebo Knut <Knut.Hellebo_at_nho.hydro.com>
masson_at_sagremor.enssat.fr (Masson Christophe)

Hope that helps,
JD
--------------------------------------------------------------------------
        Jacques DEMEULEMEESTER | e-mail : demeule_at_univ-lille3.fr
  Universiti Charles de Gaulle-Lille 3 | tel 20.41.64.19
   Centre de Ressources Informatiques | fax 20.41.63.79
         Rue du Barreau BP 149 |
     59653 Villeneuve d'Ascq cedex |
                 FRANCE |
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Received on Fri Oct 13 1995 - 17:59:56 NZDT

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