Microsoft KB Archive/277863

= Scalability of Terminal Services on Windows 2000-Based Servers =

PSS ID Number: 277863

Article Last Modified on 9/24/2003

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The information in this article 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 Q277863



SUMMARY
This article describes options for scalability of Terminal Services when you use Application mode on computers with more than 4 GB of memory.



MORE INFORMATION
Windows 2000 Advanced Server and Windows 2000 Datacenter Server can support memory that is more than 4 gigabytes (GB) of RAM by using the Intel Physical Addressing Extension (PAE) specification. Windows 2000 Advanced Server can support up to 8 GB of RAM, and Windows 2000 Datacenter Server can support up to 32 GB.

Terminal Services uses 2 GB of address space that is allocated to the kernel. When you enable the PAE switch, this address space does not increase because Terminal Services does not make use of the Address Windows Extensions (AWE) APIs. Therefore, even if your computer has more than 4 GB of RAM, there is no performance benefit if you use the PAE switch.

The session load that a system can host does not increase regardless of the amount of RAM over 4 GB that is installed. However, some programs, including Terminal Services and multiple-threaded programs, may benefit from the additional memory.

When you enable program memory tuning by using a /3GB switch in the Boot.ini file, Terminal Services performance is affected. When you use this switch, a larger virtual memory address space is created for programs but the address space for the kernel is reduced.

Because each environment is unique, the effects of using the PAE switch and the /3GB switch should be carefully evaluated before you attempt to use them to maximize performance. In some instances, a scale-out solution may be more appropriate than a scale-up solution.

NOTE: Windows 2000 Advanced Server and Windows 2000 Datacenter Server are 32-bit operating systems; the 4 GB memory limit is native to a 32-bit operating system and 32-bit processors.

For additional information, refer to the Windows 2000 Terminal Services Capacity and Scalability white paper, which can be found at the following Microsoft Web site:

http://www.microsoft.com/windows2000/techinfo/administration/terminal/tscaling.asp

For additional information about scalability, click the article numbers below to view the articles in the Microsoft Knowledge Base:

268363 Intel Physical Addressing Extensions (PAE) in Windows 2000

268230 Scaling Out Versus Scaling Up with Intel Physical Addressing Extension (PAE)

247904 How to Configure the Paged Address Pool and System Page Table Entry Memory Areas

Keywords: kbinfo kbPAE kbTermServ w2000wts KB277863

Technology: kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000DataServ kbwin2000DataServSearch kbwin2000Search kbwin2000Serv kbwin2000ServSearch kbWinAdvServSearch kbWinDataServSearch

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