Re: Does Oracle lock (pins) RAM ?

Hi Joe,

If you need good performance when using Oracle the rule of thumb is to dedicate the system to Oracle. Since Oracle buffers all writes to the data base you want to give it enough memory to make sure that the buffers don't get paged out before Oracle writes them out.

To figure out how much RAM to give Oracle look in the file init<sid>.ora (where <sid> is the Oracle instance ID) which you will find in a directory under $ORACLE_HOME (I don't remember the specific directory it's in in Unix -- but if its any help you will find it in DATABASE on both Windows 95 and Windows NT). Once you find it check the parameters out. The ones that affect RAM are the values for db_block_buffers and shared_pool_size. The smallest values I would consider using for a production system are double those Oracle specifies for a Large Data Base. You will have to experiment to find out how much more you should give to Oracle. Basically what you do is keep feeding it more memory every night and monitoring the performance during the day. When performance stops improving or the users report that they see no perceptible difference in performance from the previous day freeze the values.

For a more scientific approach buy your DBA a copy of Oracle Performance Tuning by Corrigan and Curry published by O'Reilly and Associates and a copy of High Performance Oracle Tuning by Burleson published by Coriolus Group.

Regards

Jerry

Joe Babaloo wrote:
>
> My DBA doesn't know and Oracle says they don't use plock(), however
> installation of 7.3.3.4
> requires MLOCK privilege for dba group (HP-UX) This must mean that Oracle
> pins code or data in
> physical memory for shared or regular memory, and if so my question is how
> much? Is there a way to figure out RAM requirements for Oracle. If it
> uses only virtual memory, RAM needs will depend on system load (TPM), but if
> it pins memory it's another matter.
>
> Thank you
 

-- 
Jerry Gitomer		Since I know how to spell DBA I became one. 
jgitomer_at_p3.net