Shared memory qustion

Question

Oracle 10.2.0.4, 11.2.0.1, 11.2.0.2
Oracle Linux 5.6 64bit
Development box with multiple databases
Just when I thought I was getting a handle on useage of os shared memory (/dev/shm) ......
Up unitl now, if did an 'ls -l /dev/shm', I would see segments for every running instance. That is, say I did a 'ps -ef | grep pmon' and had 'oradbA', 'oradbB' and 'oradbC' , a 'ls -l /dev/shm' would show a bunch of segments for each, 'oradbA', 'oradbB' and 'oradbC'. Now I take a look a this one server, and I only see shm segments for only one of the running instances.
And no, it's not a matter of them scrolling off the screen. I'm using putty, and logging the entire session, so I can look at the log file and see evertthing, not just what's in the screen buffer. or if I grep the ouput ...
oracle:fs91upg$ ps -ef|grep pmon|grep -v grep
oracle   13064     1  0 Jun11 ?        00:00:00 ora_pmon_fsupg
oracle   13133     1  0 Jun11 ?        00:00:00 ora_pmon_hr91tst
oracle   13229     1  0 Jun11 ?        00:00:00 ora_pmon_hr91dev
oracle   13329     1  0 Jun11 ?        00:00:00 ora_pmon_hr91dmo
oracle   13425     1  0 Jun11 ?        00:00:00 ora_pmon_hr91upg
oracle   13520     1  0 Jun11 ?        00:00:00 ora_pmon_fs9dev
oracle   13663     1  0 Jun11 ?        00:00:00 ora_pmon_fs91dmo
oracle   14295     1  0 Jun11 ?        00:00:00 ora_pmon_fs9dmo
oracle   28297     1  0 Jun12 ?        00:00:00 ora_pmon_fs91upg
oracle:fs91upg$
oracle:fs91upg$ ls /devls /dev/shm | grep fsupg
oracle:fs91upg$ ls /dev/shm | grep hr91tst
oracle:fs91upg$ ls /dev/shm | grep hr91dev
oracle:fs91upg$ ls /dev/shm | grep hr1991dmo
oracle:fs91upg$ ls /dev/shm | grep hr91upg
oracle:fs91upg$ ls /dev/shm | grep fs9dev
oracle:fs91upg$ ls /dev/shm | grep fs9dmo
oracle:fs91upg$ ls /dev/shm | grep fs91upg
oracle:fs91upg$ ls /dev/shm | grep fs91dmo
ora_fs91dmo_524298_0
ora_fs91dmo_524298_1
ora_fs91dmo_557067_0
ora_fs91dmo_557067_1
ora_fs91dmo_557067_10
<snip>

Answer 1

EdStevens wrote:
Now to go back and read Tanel's notes once again, with this in mind . . .Ed,
I can not say how grateful I am to you for asking these questions in an excellent manner. My apologies for not being able to answer your question (as I am lagging behind you when it comes to *nix OS level knowledge) but I am curious to know how this thread develops. Tanel poder's blog post, mentioned here, is, as always, excellent (and I would like to say I understood every bit of it ;) ). Not sure if it helps, but you may want to have a look at <a href="http://www.oracle.com/technetwork/articles/linux/part3-090589.html">this</a> excellent article by Arup Nanda to see if it gives you any extra information. I liked the whole 5-part series that Arup has written and I visit it from time to time.