Oracle Tips : How you know memory component size when use automatic storage memory managenent(ASMM)
Oracle Database 10g includes the Automatic Shared Memory Management feature which simplifies the SGA memory management significantly.
When automatic SGA memory management is enabled, the sizes of the different SGA components are flexible and can adapt to the needs of a workload without requiring any additional configuration. The database automatically distributes the available memory among the various components as required, allowing the system to maximize the use of all available SGA memory.
DBA can check all memory component size with dynamic view V$SGA_DYNAMIC_COMPONENT