How to find which shared memory segment corresponds to which instance.

Question

If you have two or more instances running on a unix machine, is there a way to find out which shred memory segment and what semaphores are allocated. You could do a "ipcs -a" which will give you all the shared memory segments and semaphores, but how to find what corresponds to what instance.
Thanks
Devinder
PS: I dont know whether this is correct discussion forum or not, cause I could not find anything related to it.
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Answer 1

if you type ipcs -a you could see:
ipcs -aIPC status from <running system> as of Tue Jan 30 12:02:20 EST 2001
Message Queue facility inactive.
T ID KEY MODE OWNER GROUP CREATOR CGROUP NATTCH SEGSZ CPID LPID ATIME DTIME CTIME
Shared Memory:
m 0 0x500008c7 rw-rr-- root root root root 1 68 373 373 11:48:11 11:48:11 11:48:11
m 1 0xb9359140 rw-r--- oracle dba oracle dba 28 109568000 593 8631 11:29:43 12:01:36 11:49:06
m 2 0x21d38b58 rw-r--- oracle dba oracle dba 53 83746816 654 8630 12:01:15 12:01:15 11:49:58
T ID KEY MODE OWNER GROUP CREATOR CGROUP NSEMS OTIME CTIME
Semaphores:
s 196608 0xbfb87050 ra-r--- oracle dba oracle dba 54 12:01:37 11:49:06
s 196609 0xcc222a00 ra-r--- oracle dba oracle dba 104 11:53:31 11:49:59
note that the CTIME shows you when the entry was created... they usually map to within a second between the memory segment and the semaphore (M and S). 11:49:06 and 11:49:59 in my case.
If I look in my alert_log for each instance I will see:
--Sun Jan 28 11:49:04 2001
--Starting ORACLE instance (normal)
and in the other file
--Sun Jan 28 11:49:58 2001
--Starting ORACLE instance (normal)
This lets me know which instance uses which semaphores/memory segments.
Just be sure the start your instances at least 30 seconds apart so the times are different enough.
enjoy.
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