SGA size

[sln81]

Whenever we startup the database, we see the memory allocations for SGA. But most of the times, I have observed that the logbuffer size is differnt from the parameter log_buffer in the INITSID.ora file. Can anybody tell me what do we exactly mean by fixed and variable sizes. How much of fixed size is allocated for an instance? Also V$SGAS?TAT figures sometimes do not match with tha INITSID.ORA parameters. Thanks for any information given.

[sln81]

Hi,
Waiting for reasonable answer.

[tamilselvan]

Fixed size varies depending upon the Opearting Systems.

Always ensure log_buffer is multiple of OS block size.

[aracnid]

Anything in SGA is fixed size; is defined in init.ora file, allocated at startup and freed at shutdown...anything in PGA is variable size; basically it grows/shrinks depending on demand and is only limited by the physical hardware.

[sln81]

Anything in SGA can't be fixed size. Becausse when we add the share_pool_size, db_buffer size, log_buffer: the total will much more than what is shown as fixed size.