Q. I have an Exchange Server 2003 server that runs on Windows Server 2003 and has more than 1GB of memory. What settings should I add to the boot.ini file to optimize virtual-memory usage?

A. On pre-Windows 2003 systems that have more than 1GB of memory, it was common to add the /3GB setting to the boot.ini file to optimize Exchange Information Store virtual memory usage. On a Windows 2003 system, you must specify an additional setting in boot.ini: /USERVA=3030. The /USERVA=3030 setting splits the virtual memory allocation between user mode and kernel mode. This memory allocation lets Exchange allocate an additional 40MB of memory to the kernel for page table entries, which improves an Exchange 2003 server's scalability. The following sample boot.ini entry shows the use of the /3GB and /USERVA=3030 settings:

multi(0)disk(0)rdisk(0)partition(1)
\WINDOWS="Microsoft Windows Server 2003"/fastdetect
/3GB /USERVA=3030

(The listing is shown on three lines because of space constraints.)

End of Article

Please note that accoring to this KB article, on Windows 2000 Server, this switch only applies to Windows 2000 Advanced Server and Datacenter Server. It does not apply Exchange 2000 installs on SBS or Standard Server editions.

http://support.microsoft.com/default.aspx?kbid=266096

J Wright June 01, 2004

We have Windows 2003 Enterprise installed on a server with 5GB of RAM. When we first installed W2K3, it only saw (reported) 3GB of RAM, so after a call to the server manufacturer we added the /PAE switch in the boot.ini file. Now it sees 4.75GB RAM(?).
After we installed Exchange 2003, we got messages in the event log about needing to optimize the memory for Exchange - i.e. set the /3GB /USERVA settings. So now the server's boot.ini has the following:
/fastdetect /PAE /3GB /USERVA=3030
Does this sound correct or supported? Everything appears to be working, but the server has not been stress tested yet...
Thanks, Jeremy

Jeremy A. Ellis June 01, 2004

Can I use this settings on Windows 2000 Server with Exchange 2000 Server ?
Because, I have some problem with Virtual Memory Fragmentation.

Philippe GODINHO June 02, 2004

Exchange and PAE is not a good idea. Exchange is not built to understand anything over 4GB. The /PAE (Physical Addressing Extensions) switch is a parameter that is set in Boot.ini. The /PAE switch enables a computer to access more than 4 GB of physical memory (RAM). Exchange Server cannot use more than 4 GB of physical memory, and there is no benefit to installing more than 4 GB of RAM on a computer that is dedicated to running Exchange Server. This switch may have been incorrectly set an OEM Setup program.
If the server is running another memory-intensive application (such as SQL Server 2000), this switch may have been intentionally set by an administrator to use more than 4 GB of RAM. If you are running multiple applications that require the additional memory, you can run a Windows hotfix that will help prevent Exchange store failures that might occur when there is more than 4 GB of RAM available. Note that the recommended best practice is to dedicate a computer to run Exchange Server only. For more information about the hotfix, see Microsoft Knowledge Base article 834628, "Data is corrupted when PAE is enabled on a Windows Server 2003-based computer" (<http://go.microsoft.com/fwlink/?linkid=3052&kbid=834628>).If the computer where this warning was generated is a dedicated Exchange Server computer, remove this switch from the Boot.ini file.

Anonymous User January 22, 2005

PAE is a physical extension and has nothing to do with virtual memory. To address issues with VM fragmentation if you are running Win2k advanced or datacenter you can use /3GB switch, if you are running standard your best bet is reducing the RAM to around 1 GB and implementing tewaks per follwing KBs. 325044 How to troubleshoot virtual memory fragmentation in Exchange Server 2003
http://support.microsoft.com/?id=325044
317411 How to gather data to troubleshoot Exchange virtual memory issues
http://support.microsoft.com/?id=317411
317411 How to gather data to troubleshoot Exchange virtual memory issues
http://support.microsoft.com/?id=317411
315407 XADM: The "HeapDecommitFreeBlockThreshold" Registry Key
http://support.microsoft.com/?id=315407

Anonymous User January 22, 2005

/3GB
Increases the size of the user process address space from 2 GB to 3 GB (and therefore reduces the size of system space from 2 GB to 1 GB). Giving virtual-memory- intensive applications such as database servers a larger address space can improve their performance. For an application to take advantage of this feature, however, two additional conditions must be met: the system must be running Windows XP, Windows Server 2003, Windows NT 4 Enterprise Edition, Windows 2000 Advanced Server or Datacenter Server and the application .exe must be flagged as a 3-GB-aware application. Applies to 32-bit systems only

Anonymous User July 11, 2005 (Article Rating:

)

Please reading the following update , very important.

http://bink.nu/Article4438.bink

nawar75 July 18, 2005 (Article Rating:

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