Microsoft KB Archive/311901

= The effects of 4GT tuning on system Page Table Entries =

Article ID: 311901

Article Last Modified on 10/30/2006

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APPLIES TO


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

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This article was previously published under Q311901





SUMMARY
Computers with heavy input/output (I/O) loads (for example, servers that run large installations of Microsoft Exchange or Microsoft SQL Server) may report any of the following error messages when using 4GT tuning:

Message 1

Stop 0x0000003F NO_MORE_SYSTEM_PTES

Message 2

Stop 0x000000D8 DRIVER_USED_EXCESSIVE_PTES

Message 3

1450 Insufficient system resources exist to complete the requested service



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows 2000. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to obtain the latest Windows 2000 service pack



MORE INFORMATION
To help resolve this issue, obtain an updated Scsiport.sys driver. However, depending on the use of Page Table Entries (PTEs) by third-party drivers, additional memory tuning may be required. A fix that addresses this issue is described in the following Microsoft Knowledge Base article:

311551 &quot;STOP 0x000000D8 DRIVER_USED_EXCESSIVE_PTES&quot; error message on server with heavy I/O load

You can significantly reduce system PTEs if you use 4GT tuning (this is also known as the /3GB switch). For more information about PTEs and the /3GB switch, click the following article number to view the article in the Microsoft Knowledge Base:

291988 A description of the 4 GB RAM tuning feature and the physical address extension switch

You can use the Performance Monitor display variable Free System PTEs under the Memory object to observe how many are free. Consider any value below 3000 as a minimum. With a standard Windows 2000 configuration, expect at least 80,000 free PTEs, and at least 15,000 free PTEs when you use the /3GB switch.

In Windows 2000, the system PTE space is located in the kernel address space with a 2-gigabyte (GB) limit. When you use the /3GB switch, the available address space is reduced to only 1 GB of operating system space. This 1 GB is reserved to load the operating system, all the page table entries, and the pools. As a result, the operating system will have only a fraction of the system PTE space available that is available under the standard memory model.

A range of 80,000 to 140,000 system PTEs is available in a standard configuration, while only 40,000 PTEs are available when using the /3GB switch. Due to the nature of the tuning algorithm, fewer pages may be available than the numbers that are described in this article.



WORKAROUND
To work around this issue, do the following:  Make sure that your drivers are not using any switches or parameters to reduce or eliminate the use of system PTEs. Examples of drivers that may use such switches are the hard disk driver, the network adapter driver, and also AGP video cards that map physical memory. Remove any registry entries under the memory management key for Page table entries or for Paged pool maximum entries. These entries are very useful for tuning the standard installation. Remove these entries when using the /3GB switch. For more information about changing these registry entries, click the following article number to view the article in the Microsoft Knowledge Base:

247904 How to configure the Paged Address Pool and System Page Table entry memory areas

 Do not use the /PAE switch. Changing this value does not change the number of PTEs that are created. Using the /PAE switch instructs the memory manager to use two PTEs to map every page of memory. For more information about using the /PAE switch, click the following article number to view the article in the Microsoft Knowledge Base:

268363 Intel Physical Addressing Extensions (PAE) in Windows 2000



