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Spotlight on Oracle 10.10 - Release Notes

Fine Tune Memory Components

There are five steps to use the Memory Management Page. This page documents Step 3.

Ensure you are satisfied with the memory management mode and global memory allocations before you fine tune memory components. You should review all your changes against the charts. Remember, you can use this page to investigate the impact of making changes without applying those changes. If appropriate, there is a procedure to apply changes as documented in the last step.

To use the Memory Management Page

  1. Select A Memory Management Mode And Allocate Global Memory
  2. Review Your Changes Against The Charts
  3. Fine Tune Memory Components
  4. Review Your Changes Against The Charts
  5. Apply Changes

 

Memory Components

See how the Current Oracle memory is allocated, and how Oracle Advisories Calculate that memory SHOULD be allocated in the selected memory mode.

To customize the calculated value click Edit.

Note: Some Oracle memory components are allocated and freed in units called granules.

Review the effect of the changes: Review Your Changes Against The Charts.

Column Description Applicable Modes
Component

The name of the Oracle memory component:

  • Database Buffers

  • Shared Pool

  • Large Pool

  • Java Pool

  • Other

  • PGA Aggregate Target

Note: View Database Buffers as a single item or expand the tree to view individual cache components.

 All
Current value

The current size of the component in megabytes.

 Manual
Calculated value

The recommended size of the component according to the Oracle advisory as based on the selected memory mode and allocation of global memory.

Double click on the row to customize the size. Customized sizes are shown in bold text.

 Manual
Current minimum Oracle cannot shrink the component below this value, but the component can grow using dynamic memory. ASMM and AMM
Calculated minimum

The recommended minimum size for the component according to the Oracle advisory as based on the selected memory mode and allocation of global memory.

Double click on the row to customize the size. Customized sizes are shown in bold text.

ASMM and AMM

Granule Size in SGA

In the dynamic SGA model, SGA memory components are allocated and freed in units called granules. A granule cannot be shared among multiple SGA components.

Granule size is platform-dependent and is determined largely by the total (maximum) SGA size.

  • On most Unix platforms, including Solaris, if the total SGA size is less than 128 MB, the granules are 4 MB in size. Otherwise they are 16 MB.
  • On Windows, the largest granule size is 8 MB if SGA_MAX_SIZE is greater than 128 MB, and 4 MB otherwise.

Note: In earlier versions of Oracle, the implementation of the System Global Area (SGA) allows the operating system-dependent code to determine the minimum size of an individual allocation for a particular subsystem requiring memory. The buffer cache, the shared and large pools, and the redo buffers were treated as independent logical sections of the SGA, with the product lines determining the minimum allocation sizes and other attributes for shared memory.

 

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