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This Exchange server has less than 1 GB of memory but has the /3GB switch set in the Boot.ini file

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries two Microsoft Windows® Management Instrumentation (WMI) classes to determine the amount of physical memory in the Exchange Server computer and the amount of virtual address space allocated to user mode processes running on the Exchange Server computer. The following table describes the classes and keys being evaluated by the Exchange Server Analyzer.

 

Class queried Keys queried Description

Win32_OperatingSystem

MaxProcessMemorySize

Maximum number of kilobytes of memory that can be allocated to a process.

Win32_ComputerSystem

TotalPhysicalMemory

Number of bytes of random access memory (RAM) installed on the computer.

If the Exchange Server Analyzer determines that the value for TotalPhysicalMemory is less than 1073741824, and that the value for MaxProcessMemorySize is equal to 3145600, a warning is displayed.

This warning indicates that the system has less than 950 megabytes (MB) of physical memory, but it has been configured with the /3GB startup switch in the Boot.ini file. This switch should only be used on Exchange Servers with 1 gigabyte (GB) or more of memory that are running any of the following operating systems:

  • Microsoft Windows Server™ 2003 Standard Edition

  • Microsoft Windows Server 2003 Enterprise Edition

  • Microsoft Windows Server 2003 Datacenter Edition

  • Microsoft Windows 2000 Advanced Server

  • Microsoft Windows 2000 Datacenter Server

importantImportant:
The /3GB switch should not be used on Windows 2000 Server because it is unsupported and can cause application or operating system crashes. Furthermore, the /3GB switch is only supported on the operating systems listed previously when 1 GB or more of physical memory is installed.

If you encounter this warning on a system in which 1 GB of physical memory is installed, it could indicate that another component, such as a video card, has been allocated some of this physical memory at the hardware level, thereby making the allocated physical memory unavailable to the operating system. In these cases, the amount of memory installed physically according to Windows will be less than the actual amount of physical memory installed in the computer. If you encounter this situation, you should compare the amount of installed memory reported by the BIOS with the amount of installed memory reported by Windows.

  1. Right-click My Computer, and then click Properties. The System Properties dialog box appears.

  2. Click Advanced.

  3. In the Startup and Recovery area, click Settings. The Startup and Recovery dialog box appears.

  4. In the System startup area, click Edit. This will open the Windows Boot.ini file in Notepad.

  5. In the [Operating Systems] section, delete the following switches from all startup lines: /3GB

  6. Save the changes and close Notepad.

  7. Click OK twice to close the open dialog boxes and then restart the computer for the change to take effect.

  1. In Windows Explorer, navigate to the System Partition. This is the partition that holds the hardware-specific files such as Boot.ini and NTLDR.

  2. If you cannot see the Boot.ini file, it could be because the Folder Options are set to Hide protected operating system files. If this is the case, in the Windows Explorer window, click Tools, click Folder Options, and then click View. Clear the Hide protected operating system files (Recommended) check box. When prompted, click Yes.

  3. When the Boot.ini file is visible in Windows Explorer, right-click the file, click Open With, and then click Notepad to open the file.

  4. In the [Operating Systems] section, delete the following switches from all startup lines: /3GB

  5. Save the changes and close Notepad.

  6. Restart the computer for the change to take effect.

For more information about optimizing memory usage for Exchange Server, see the following Microsoft Knowledge Base articles:

 
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