Re: 8.1.7 on redhat 7.3 - not freeing memory

Scott Dudley <scott_at_nospam.telesoft.com> writes:
> we recently installed 8.1.7 on a dual processor, compaq proliant
> running redhat 7.3 with 4gb ram. one of our support staff asked me
> this morning why when oracle starts, does it quickly consume all
> available memory and then when shut down, does not free it. i've
> never observed this and suspect it has something to do with shared
> memory. can someone help me to address his question/concern?

Err,

when you shut down oracle database and all the processes are gone, some memory remains allocated? Very interesting. If you first say $ free

             total       used       free     shared    buffers     cached
Mem:        256676     167956      88720          0         76     125300
-/+ buffers/cache:      42580     214096
Swap:       525304      43188     482116

and look at "free" column at "row -/+ buffers/cache", then start/stop db like this:
$ svrmgrl

SVRMGR> connect internal as SYSDBA
SVRMGR> startup open
SVRMGR> shutdown immediate
SVRMGR> quit

and verify that no oracle processes remain by saying $ ps ax | grep ora

now, what is now the output of free? If you repeat this a few times, do you see more memory being allocated or what?

> Mem: 4387980K av, 4367712K used, 20268K free, 0K shrd,

this "top" output includes buffers, so during normal operation there is no free memory, everything is and must always be used except for a very small amount, like here this 20268K.

--
Antti