Microsoft KB Archive/896066

= Less memory than you expect may be reported in Windows 2000 Server =

Article ID: 896066

Article Last Modified on 6/17/2005

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Datacenter Server

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SYMPTOMS
On a Microsoft Windows 2000 Server-based computer that has 4 gigabytes (GB) of random access memory (RAM), the System Properties dialog box and the System Information dialog box may report less memory than you expect.

Notes
 * To open the System Properties dialog box, click Start, click Run, type sysdm.cpl, and then click OK.
 * To open the System Information dialog box, click Start, click Run, type msinfo32.exe, and then click OK.



CAUSE
This behavior occurs because of the 4-GB address space limitation in Windows 2000 Server. Because of this limitation, Windows 2000 Server cannot access the memory that is relocated above the 4-GB boundary. The memory is relocated to allow for addresses that the BIOS reserves for hardware.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
Windows 2000 Advanced Server and Windows 2000 Datacenter Server can support systems with more than 4 GB of RAM. Windows 2000 Advanced Server and Windows 2000 Datacenter Server can address memory that is relocated above the 4-GB boundary if the following conditions are true:
 * The computer is in Physical Address Extension (PAE) mode.
 * The computer has 4 GB of RAM.

In this case, these operating systems correctly report the amount of memory that is installed.

Note You enable PAE mode by adding the /PAE switch to your Boot.ini file. The Boot.ini file is in the root directory of your system drive.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

268230 Scaling out versus scaling up with Intel Physical Addressing Extensions (PAE)

283037 Large memory support is available in Windows Server 2003 and in Windows 2000

If you add more memory to the system, it is possible that the BIOS will recognize the full amount of physical RAM that is installed in the server but that Windows will recognize only a part of the RAM. If the server has a redundant memory feature or a memory mirroring feature that is enabled, the full complement of memory may not be visible to Windows. Redundant memory provides the system with a failover memory bank when a memory bank fails. Memory mirroring splits the memory banks into a mirrored set. Both features are enabled or disabled in the BIOS and cannot be accessed through Windows. To modify the settings for these features, you may have to refer to the system user manual or the OEM Web site. Alternatively, you may have to contact the hardware vendor.

For example, if you are running a system that has 4 GB of RAM installed and you then add 4 GB of additional RAM, Windows may recognize only 4 GB of physical memory or possibly 6 GB instead of the full 8 GB. The redundant memory feature or the memory mirroring feature may be enabled on the new memory banks without your knowledge. These symptoms are similar to the symptoms that occur when you do not add the /PAE switch to the Boot.ini file.

Keywords: kbtshoot KB896066

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