SGA fixed size & variable size

[ocp2b]

What parameter(s) affect the fixed size and variable size values in the SGA? Example:

Show SGA

Total System Global Area 72520972 bytes
Fixed Size 70924 bytes
Variable Size 30838784 bytes
Database Buffers 40960000 bytes
Redo Buffers 651264 bytes

[sambavan]

Different sub-divisions of the SGA
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Sample from svrmgrl SHOW SGA:

Total System Global Area 23460696 bytes
Fixed Size 72536 bytes
Variable Size 22900736 bytes
Database Buffers 409600 bytes
Redo Buffers 77824 bytes

Total System Global Area
- Total in bytes of all the sub-divisions that makes up the SGA.

Fixed Size
- Contains general information about the state of the database and the
instance, which the background processes need to access.
- No user data is stored here.
- This area is usually less than 100k in size.

Variable Size
- This section is influenced by the following init.ora parameters
shared_pool_size
large_pool_size
java_pool_size
- See 'Approximating Size of the SGA' section of this article for version
specific information.

Database Buffers
- Holds copies of data blocks read from datafiles.
size = db_block_buffers * block size

Redo Buffers
- A circular buffer in the SGA that holds information about changes made to
the database.
- Enforced mininum is set to 4 times the maximum database block size for the host operating system.

Sam