AWE function in SQLSERVER

The AWE function in SQL server has a virtual address space of 4 GB for 32-bit Windows user processes. 2 GB for the core state, and 2 GB for the user State. These two parts are strictly separated. In Windows, the memory address space of one of these blocks is not used up, but the space of the other block is not transferred out. Because most SQL Server commands run in user mode, that is, SQLS

The AWE function in SQL server has a virtual address space of 4 GB for 32-bit Windows user processes. 2 GB for the core state, and 2 GB for the user State. These two parts are strictly separated. In Windows, the memory address space of one of these blocks is not used up, but the space of the other block is not transferred out. Because most SQL Server commands run in user mode, that is, SQLS

AWE function in SQLSERVER

Because 32-bit Windows user processes have 4 GB virtual address space. 2 GB for the core state, and 2 GB for the user State. These two parts are strictly separated. Windows will not

When the memory address space is exhausted, the other part of the space is freed.

Because most SQL Server commands run in user mode, the memory of SQL Server basically uses user-mode address space resources. The current situation is 2 GB address space resources

For SQLSERVER, it seriously hinders SQLSERVER from using hardware resources effectively.

Therefore, SQLSERVER introduces AWE address windowsing extensions (address space extension ). This allows 32-bit applications to allocate 64 GB physical memory, and puts the view or window

Ing to 2 GB virtual address space.

With AWE, an application can access up to 64 GB of physical memory !!!

In the Enterprise Edition of SQL2000, both the Enterprise Edition and Standard Edition of SQL2005/2008 support this technology and enjoy the benefits brought by this technology.

To enable this function, restart the SQL Server service after execution.

1 EXEC sys.sp_configure @configname = 'AWE Enabled', -- varchar(35)2     @configvalue = 1 -- int3 RECONFIGURE4 GO

AWE implementation Diagram

Note the following:

(1) enabling this function requires SQLSERVER to enable the lock pages in memory permission of the account on Windows. Without this permission, AWE cannot be enabled successfully.

At this time, only 2 GB of address space can be used for SQL server startup.

The DBA needs to check whether there is any relevant information in the errorlog of SQLSERVER.
Enabled successfully: server Address extenwing Extensions enabled
Message
Address wing Extensions is enabled. This is an informational message only; no user action is required.
Failed to enable: Cannot use Address processing wing Extensions because lock memory privilege was not granted

(2) This function is consciously used at the application level, rather than at the Windows level. That is to say, when SQL Server applies for memory, it applies through a special API call,

If SQLSERVER does not call this function, it will apply for memory in the normal 2 GB virtual address space. In SQLSERVER, not all memory applications call AWE technology,

SQLSERVER uses AWE to enable them to use the extended memory only when reserve and commit memory calls are performed. The memory requested by other methods can only use a normal 2 GB address space.

Because of this, AWE cannot be called the final solution to solve the problem of insufficient SQL server address space. With a 64-bit server, the virtual address space can reach 8 TB,

It is larger than the physical memory of the vast majority of individual servers. The performance of SQLSERVER running in 64-Bit mode is usually significantly higher than that in 32-Bit mode.

The maximum memory size supported by each version of Windows is attached.
Configure the maximum physical memory size of the virtual address space of the application. Whether AWE/locked pages support is supported
32-bit SQLSERVER 2 GB 64 GB YES
32-bit SQLSERVER +/3 GB boot. ini parameter 3 GB 16 GB YES
32-bit SQLSERVER application in x64 Operating System (WOW) 4 GB 64 GB YES
32-bit SQLSERVER application in IA64 Operating System (WOW) 2 GB 2 GB NO
64-bit SQLSERVER application in x64 operating system 8 TB 2 TB YES
64-bit SQLSERVER application in IA64 Operating System 7 TB 2 TB YES