How to use more than 4 GB of RAM for Oracle database on 32 bit Windows using AWE

By PhDs, (© Copyright reserved), April 19, 2007 at 11:17 am · Category: Oracle DBA

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How to use more than 4 GB of RAM for Oracle database on 32 bit Windows using AWE(Advanced Windowing Extentions, or another term: Physical Address Extensions, PAE)

Configure Windows and Oracle using the following steps.

1, Make sure you have installed one of the following OS software:

* Windows 2000 Datacenter Server
* Windows 2000 Advanced Server
* Windows 2003 Data Center Edition (32-Bit)
* Windows 2003 Enterprise Edition (32-Bit)

Other OS version won’t work. For example, if you have installed Windows 2003 Standard Edition, sorry, you are out of luck.

If you have installed 64-Bit Windows operating systems, there is no need for AWE. You can use up to 8 terabytes of memory for a single processor on 64-Bit Windows.

2, The following Oracle versions will support AWE:

* Oracle 8.1.6.x
* Oracle 8.1.7.x
* Oracle 9.2.x
* Oracle 10g.

3, Enabling support at the OS level. AWE can be enabled at the OS by adding the /PAE switch to the boot.ini:

multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Advanced Server" /PAE

another example is to use this:

multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Advanced Server" /3GB /PAE

These configurations will allow Oracle to use up to 16 Gbytes of RAM.

4, Grant ‘Lock Pages in Memory’ Operating System Privileges to OS Oracle user account.

Go to Start -> Programs -> Administrative Tools -> Local Security Policy (on a Domain Controller, click on ‘Domain Security Policy’ instead of ‘Local Security Policy’), Double-click on the ‘Lock Pages in memory’ policy, Add the appropriate user and click ‘Ok’.

5, Set AWE_WINDOW_MEMORY to desired value. The size of AWE_WINDOW_MEMORY is defined by a registry setting in the HOME key for Oracle (HKLM\Software\Oracle\Homex) called AWE_WINDOW_MEMORY. If this value is not set in the registry, the size of AWE_WINDOW_MEMORY is 1GB by default.

6, Enabling AWE Support at the Database/Instance Level:

To enable the AWE implementation on Oracle, you must set the following parameter in the init file (or spfile) used to start the instance:

USE_INDIRECT_DATA_BUFFERS=TRUE

The total size of the buffer cache can then be set to the amount of physical memory remaining above the 4GB barrier, plus AWE_WINDOW_MEMORY. For example, on a server machine with 12GB of RAM, your total buffer cache could be set as high as 9GB if default value of 1GB is used for AWE_WINDOW_MEMORY:

(Total RAM - 4GB + AWE_WINDOW_MEMORY) = 12GB - 4GB + 1GB = 9GB

So with 8K block size (8192), you can set 9 Gbyte for DB_BLOCK_BUFFERS. You sould comment out dynamic parameter DB_CACHE_SIZE=xxxxx because DB_CACHE_SIZE and DB_BLOCK_BUFFERS are mutual exclusive.