The /USERVA Switch
Those of you that have ever had an Exchange 2000 server with more than 1GB RAM configured in it will no doubt be aware of the /3GB switch that should be placed in boot.ini on that server. This ensures that 3GB of memory is available for user-mode applications and has been well documented in various Microsoft KB articles.
A new boot.ini switch is available in Windows 2003 that is important to Exchange 2003 installations: the /USERVA switch. When Exchange 2003 is installed on a Windows 2003 server that has more than 1GB RAM configured in it, it is important to add the new /USERVA switch as well as the /3GB switch into the boot.ini file. The format for the new /USERVA switch is /USERVA=3030. For example, the relevant portion of the boot.ini file may look like this:
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows Server 2003" /fastdetect /3GB /USERVA=3030
It is important to ensure that the value of 3030 is used for the /USERVA switch. This value ensures that an additional 42MB of memory is allocated to the kernel for page table entries, meaning that you can then host a greater number of users on the server.
Don't forget that this switch should only be used on Windows 2003 servers.
If you need deeper technical information on this subject, try this Microsoft KB article.
Account Deleted on November 12, 2003 at 04:00 AM in Useful Info
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Listed below are links to weblogs that reference The /USERVA Switch:
» 3GB switch for Exchange from KWSupport
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Tracked on May 3, 2004 5:03:46 PM
» >3GB mem in Exchange on w2k3 from Absoblogginlutely
I knew about the /GB switch with exchange as there was more than 1GB line on the machine but I didn't know about the The /USERVA Switch switch. I do now though!... [Read More]
Tracked on Jan 20, 2005 1:57:54 AM
» >3GB mem in Exchange on w2k3 from Absoblogginlutely
I knew about the /GB switch with exchange as there was more than 1GB line on the machine but I didn't know about the The /USERVA Switch switch. I do now though! What I'd like to know is that if... [Read More]
Tracked on Jan 20, 2005 1:59:42 AM
Comments
This is incorrect. The /3GB swith is only supported on Enterprise editions of Windows 2003 and 2000. The switch will work on a standard server so that vendors can test their software, however it won't allocate additional memory to the application side. It will decrease available memory to the OS however, so using the switch on stadard server could decrease system performance. Look up the details on MSDN if you want a more details explanation.
Posted by: Michael Cooper at Mar 12, 2004 1:08:38 PM
Given that the /3GB switch is supported with all versions of Windows Server 2003, and MSFT in fact recommend that it is set on Exchange 2003 servers with more than 1GB of physical RAM (http://support.microsoft.com/?id=325044) I would be most interested to read the article/information that states that when used on a W2K3 Standard Server, performance is decreased.
Posted by: Chris Meirick at Mar 12, 2004 3:45:33 PM
Check KB 815372. States that the /3GB switch is supported on all releases of Windows Server 2003 including standard. Can cause problems on Windows Server 2000 Standard.
Posted by: cate at Sep 14, 2004 2:22:42 PM
