I was spending my day installing 32-bit Windows 2003 Standard Edition on one of our home build server with 4GB of RAM. Even thought the server could run x64 version of the operating system, I decided to install 32-bit Windows 2003 Standard Edition (the reason is out of the scope of today topic).

I know, that in the Windows 2000 time frame, only Advanced Server and Datacenter Server could really support 3GB user virtual memory space. Even thought, you could turn on /3GB switch on Windows 2000 Server and/or Windows 2000 Professional, the user virtual memory space is still limited to 2GB. Microsoft allowed this to help device driver developers – they could write and test the code without the need for Advanced Server.

The question that I asked myself was simple – is it possible to turn on /3GB switch on Windows 2003 Standard Edition? The answer is yes, but…According to Microsoft KB article “291988 A description of the 4 GB RAM Tuning feature and the Physical Address Extension switch” the /3GB switch in Windows 2003 Standard Edition is supported in production only for servers running Active Directory (DC). In all other cases, /3GB switch on W2K3 Standard Edition is not really supported by Microsoft; if application vendor is willing to take the risk – fine, otherwise you’re on your own.

I decided not use use /3GB switch – I’m not willing to take a chance, besides, the system will serve batch processing with little impact on system memory (up to 500MB) and the rest (up to 2GB) will be more than enough to run non-production Oracle XE instance.

On the bright side, I found some really good material on /3GB switch, searching the forum.sysinternals.com, I found excellent articles posted by Raymond Chen, a long time Microsoft employee and the author of the book “The Old New Thing: Practical Development Throughout the Evolution of Windows”.

Since /3GB switch (Virtual Memory in general) is so often miss understood, I’m sure you’ll enjoy reading short articles published by Raymond Chen on his blog:

http://blogs.msdn.com/oldnewthing/archive/2004/08/22/218527.aspx