How Big Should I Make the Shared Pool on My New Server?

Initial SGA Size Calculation

Instead of using the Oracle sample values, use the following rule of thumb
when setting the SGA size for a new system:

1. Server Physical Memory × .55 = Total Amount of Memory to Allocate to All SGAs (TSGA)
   
2. TSGA/Number of Oracle Instances on the Server = Total SGA Size Per Instance (TSGAI)
   

Using this TSGAI value, you can then calculate the SGA sizing for each individual instance:

• TSGAI × .45 = Total Memory Allocated to the Shared Pool

•  TSGAI × .45 = Total Memory Allocated to the Database Buffer Cache

•  TSGAI × .10 = Total Memory Allocated to the Redo Log Buffer