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Enabling Memory Support for Over 4 GB of Physical Memory

Updated: 14 April 2006

To enable Address Windowing Extensions (AWE) for Microsoft SQL Server, you must run the SQL Server 2005 Database Engine under a Microsoft Windows account that has been assigned the Lock Pages in Memory option and use sp_configure to set the awe enabled option to 1. The Maximize data throughput for network application option of Network Connection in Control Panel must be selected.

ms179301.note(en-US,SQL.90).gifNote:
Support for AWE is available only in the SQL Server 2005 Enterprise, Standard, and Developer editions and only applies to 32-bit operating systems. SQL Server 2005 Analysis Services (SSAS) cannot take advantage of AWE mapped memory. If the available physical memory is less than the user mode virtual address space, AWE cannot be enabled.

This policy determines which accounts can use a process to keep data in physical memory, preventing the system from paging the data to virtual memory on disk. The Lock Pages in Memory option is set to OFF by default in SQL Server 2005. If you have system administrator permissions, you can enable the option manually by using the Windows Group Policy tool (gpedit.msc) and assign this permission to the account that SQL Server is running.

For more information about how to enable the Lock Pages in Memory option, see How to: Enable the Lock Pages in Memory Option (Windows).

Although it is not required, we recommend locking pages in memory when using 64-bit operating systems. For 32-bit operating systems, Lock pages in memory permission must be granted before AWE is configured for SQL Server.

To enable AWE for an instance of SQL Server 2005, use sp_configure to set the awe enabled option to 1, and then restart SQL Server. Because AWE is enabled during SQL Server startup and lasts until SQL Server shutdown, SQL Server will notify users when awe enabled is in use by sending an "Address Windowing Extensions enabled" message to the SQL Server error log. For more information about the awe enabled configuration option, see awe enabled Option.

If the Maximize data throughput for file sharing option is selected in Network Connection, the operating system gives priority to applications that perform buffered input/output (I/O) operations by caching their I/O pages in file system cache. This option may limit memory available to SQL Server for normal operation.

To check the current setting on your operating system:

  1. In Control Panel, double-click Network Connections, and then double-click Local Area Connection.
  2. On the General tab, click Properties, select File and Printer Sharing Microsoft Networks, and then click Properties.
  3. Select Maximize data throughput for network applications, click OK, and then close the rest of the dialog boxes.

For more information about using AWE, see the Windows documentation.

Release History

14 April 2006

Changed content:
  • Added Standard Edition to the note describing editions supporting AWE.
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