How much memory can SQL Server 2005 x86 use when installed on Windows Server 2008 x64?

If I install SQL Server 2005 x86 on Windows Server 2008 x64 how much memory will SQL be able to use be default? How much after setting SQL server’s AWE switch?

This post talks about using /3gb, /PAE, and AWE to utilize SQL Server 2008 x86 memory appropriately on Windows Server 2008 x86.

My hypothesis based on that post and related information I have seen elsewhere is that by default a SQL Server 2005 x86 instance will be able to use 4GB of memory on Windows Server 2008 x64 and if I enable AWE then SQL will be able to use as much memory as the OS’s sees.

PS: Please note if your answer generalizes to other version of SQL and or Windows Server.

Thanks

x86 processes with the LargeAddressAware bit set (like sqlservr.exe) get a full 4 GB VAS for themselves. Enabling AWE (on OS and SQL editions that support it) allows the SQL server instance to map extra pages (up to 64GB) in and out of its VAS and use them for the buffer pool.

That being said, x86 is a dead end and you should switch to an x64 instance ASAP.

• Best Practices for WOW64
• Memory Architecture
• Q and A: x64 & AWE mechanism

Check more discussion of this question.

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