Can you kindly define and explain of lock_sga parameter?each flatform(HP, IBM, SUN) recommended value of both parameter
and why it is recommended like that value.
LOCK_SGA locks the entire SGA into physical memory. It is usually advisable to lock the SGA into real (physical) memory, especially if the use of virtual memory would include storing some of the SGA using disk space. This parameter is ignored on platforms that do not support it.
Each platform has its own recommendations and support over the parameter value. Hence you would see differences in the recommendations.
+ lock_sga Only locks the entire SGA into physical memory.
+ It can be set to TRUE as long as you want to lock the entire SGA in the physical memeory and your OS supports it. As for as i know it works in all the platforms.
LOCK_SGA locks the entire SGA into physical memory. It is usually advisable to lock the SGA into real (physical) memory, especially if the use of virtual memory would include storing some of the SGA using disk space.
NOTE:: This parameter is ignored on platforms that do not support it.
+ Windows For sure doesn’t support this parameter.
+ AIX Supports it.
+ LOCK_SGA is not supported on Solaris.
+ On Hp-UX if you have mlock (OS privilege) then LOCK_SGA is not required
+ Linux also supports this parameter
You can also review
Note 577898.1 – ORA-27102 Received At Startup When LOCK_SGA Is Set Although Enough Memory Is Available.
lock_sga: Default value: false.
If set to true, the entire SGA will be locked into physical memory (preventing it from being paged out). This may cause problems on systems with insufficient physical memory.
The parameters (and recommendations) are Unix generic.
The lock_sga parameter (which default AND recommended value is false): If you have sufficient memory on the server, you may consider setting it to true. (Forcing the SGA to be locked in physical memory).
On the other hand, if lock_sga is set to true, and you do not have suffficient memory, the SGA will stay in memory, and force other processe, like server processes to swap, and hence cause performance degradation.
For both the hidden and normal configuration parameters, we do not recommend deviations from the default values, without having detailed information on your specific configruation.
If you look at all Oracle products, options, features and parameters, there are billions of combinations. We do not have a complete catalog over each recommended values for each combiantion.