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Semaphores and /etc/system file

Posted on 1997-03-27
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I have two Solaris 2.5 boxes that I need to enable the semaphores on for installation of HP Openview.  After adding forceload and set statements per the install book, ipcs enables the semaphores on one box but not the other.  Doesn't help to copy the /etc/system file over from the working box.  I can enable the semaphores in Solaris 2.3 fine with those same values.  Yes, I reboot after the changes.  How can you tell if the shmsys and semsys modules are loaded?  Can anyone help me?
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Question by:girlwonder
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pxh earned 100 total points
ID: 1292471
I don;t know why you say "ipcs enables the semaphores". ipcs (InterProcessCommunicationStatus) does not en- (or dis-)able anything. It is used to check, e.g. enter "ipcs -s", it will return something like:

IPC status from <running system> as of Fri Mar 28 13:29:15 1997
T     ID     KEY        MODE       OWNER    GROUP
Semaphores:

if semaphores are enabled (but in the above example none are present). On the other hand, if you get

IPC status from <running system> as of Fri Mar 28 13:31:31 1997
Semaphore facility not in system.

your /etc/system file does not support them.

Here is an example from my /etc/system:

 set shmsys:shminfo_shmmax=268435456
 set semsys:seminfo_semmap=64
 set semsys:seminfo_semmni=4096
 set semsys:seminfo_semmns=4096
 set semsys:seminfo_semmnu=4096
 set semsys:seminfo_semume=64
 set semsys:seminfo_semmsl=100
 set shmsys:shminfo_shmmin=100
 set shmsys:shminfo_shmmni=1024
 set shmsys:shminfo_shmseg=1024

As you can see, there is quite generous shm support as well on my machine (Ultra1, running Solaris 2.5).

Then there is also a library function, which allows you to check system resources: look for "sysconf" in the man pages. It is a very simple to use routine, which returns the current values. E.g.
sysconf(_SC_SEM_NSEMS_MAX) will return the "Max number of semaphores that a process may have".

I know about one particular difference between Solaris 2.5 concerning the /etc/system file: "set enable_sm_wa = ..." is not needed (nor supported). If you copied it from you Solaris 2.3 machine, remove it on the 2.5 system.


Good luck,

Peter (pxh@mpe-garching.mpg.de)

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Expert Comment

by:plambert
ID: 1292472
You can obtain information of the actual parameters of
the system, running the following command:

      #sysdef -i

This command shows the actual values of the parameters
of the system like this (between others):

*
* IPC Messages
*
   100      entries in msg map (MSGMAP)
  2048      max message size (MSGMAX)
  4096      max bytes on queue (MSGMNB)
    50      message queue identifiers (MSGMNI)
     8      message segment size (MSGSSZ)
    40      system message headers (MSGTQL)
  1024      message segments (MSGSEG)

These values are loaded the first time you load the module
of msg. Test it!

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by:girlwonder
ID: 1292473
PXH has good advice, but doesn't need to start out the answer in, what I perceive, as a snotty way.  The answer could have been started with the third sentence.  Not all of us have had the privilege to be as trained in UNIX as we should be.  I have two college degrees, am a CNE, and am by no means slow.  My work environment is very, very dynamic and I don't normally don't have time to sit down and study.  Also, I have everything from Novell 3.x and 4.x to UNIX to Windows NT to Windows 95 and comms to support.  Maybe someday I will get funding approved for additional UNIX training, but in the mean time, I have to dig and sweat out heavy UNIX questions.  I look forward to getting some support at this site and have recommended it to many of my professional contacts.
Thank you.
girlwonder
 
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Expert Comment

by:pxh
ID: 1292474
girlwonder,

sorry, if I had a tone you didn't like, this was certainly not intended. Please accept my excuses and allow me to add that since I am German, I might miss some subtelties in my own writing. Anyhow, "snotty" is not in my vocabulary nor in my dictionnary, so I can only guess what you really critisized. Also, please under stand my situation, I read your question and the other information you give. Then I have to understand what the problem is or could be. I also have to consider that somebody else might lateron read the question/answer. So if I find something which seems imprecise in the question I have several reasons to correct it in the answer, first it might really be a misunderstanding by the questions author and second I don't want it inherited into the archive of expert-exchange.

So I was really surprised about your comment and that you seemed to take something personally, which absolutely wasn't meant that way.

Best regards,

Peter
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