How to find out semaphore usages

[nassrin5]

Hi,

I am finding out about my oracle environment and I want to know the command utility on Solaris 8 to know what semaphores being used. What is a simple description of semaphore.

thanks

 

[nassrin5]

Hi
A semaphore is an interprocess communication (IPC) in UNIX. Semaphore is basically is a hardware or software flag used to prevent processes from accessing the same shared memory space at the same time. When a process has control of a shared memory resource, all other processes are locked out of the shared memory resource until the process releases the resource. Oracle uses semaphores for protecting the shared memory resource being used. The user could be an Oracle process itself or a server side user connection..

To find out about the cative shared memory being used do:

crfxd1:/dbdumps/mapsrv% ipcs -sa
IPC status from <running system> as of Friday September  5 12:18:09 GMT 2003
T         ID      KEY        MODE        OWNER    GROUP  CREATOR   CGROUP NSEMS   OTIME    CTIME 
Semaphores:
s      65536   0x81006c13 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 15:48:22 15:43:45
s          1   0x81006c14 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:17:26 15:44:25
s          2   0xc1006c1b --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:44:25
s          3   0xc1006c19 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:44:33
s          4   0xc1006c16 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:44:33
s          5   0xc1006c1a --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:44:33
s          6   0xc1006c18 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:44:41
s          7   0xc1006c17 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:48:06
s          8   0xc1006c15 --ra-ra-ra-   oracle   oracle   oracle   oracle     2 12:18:00 15:48:22

Hope this helps

 

[nassrin5]

Well I got a bit of help from my mate. Someone else may find it useful