Server scalability

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Server scalability

This topic contains a brief overview of the features that support server scalability. It is divided into three sections: New and updated features since Windows Server 2003 (without SP1), New and updated features since Windows NT 4.0 and New and updated features since Windows 2000.

For links to more information about the features in this release, see New Features.

Scalability is the measure of how well a computer, service, or application can grow to meet increasing performance demands. For server clusters, it is the ability to incrementally add one or more systems to an existing cluster when the overall load of the cluster exceeds its capabilities. Products in the Windows Server 2003 family scale from small workgroups to enterprise data center deployments, and they support up to 64 processors and advanced I/O. The Windows Server 2003 family also integrates network load balancing and multiprocessor optimizations for your business applications.

New and updated features since Windows Server 2003 (without SP1)

Windows Server 2003 operating systems with Service Pack 1 (SP1) offer the following improvements (compared to Windows Server 2003 without SP1) that help provide increased levels of server scalability:

  • Physical Address Extension (PAE)
    To support the addition of Data Execution Prevention (DEP), which is also known as no-execute page protection, the following changes have been made:

    • PAE is automatically enabled on computers running Windows Server 2003 with Service Pack 1 and Windows XP with Service Pack 2 when DEP is also enabled on a computer with a processor that supports the no-execute page protection feature.

    • When PAE mode is enabled on computers running Windows Server 2003, Standard Edition with Service Pack 1 and Windows XP with Service Pack 2, physical address space is limited to 4 gigabytes (GB). Limiting physical address space to 4 GB helps prevent driver compatibility issues with PAE mode.

New and updated features since Windows NT 4.0

The Windows Server 2003 family offers the following improvements (in comparison to Windows NT) that help provide increased levels of server scalability:

  • Hardware scalability
    By choosing from products in the Windows Server 2003 family, you can take advantage of the growing number of competitively priced multiprocessor computers.
  • I2O support
    I2O (also called Intelligent Input/Output) architecture provides for higher I/O performance on your servers by offloading certain I/O operations to a secondary processor. I2O improves I/O performance in high-bandwidth applications, such as networked video, groupware, and client/server processing.
  • Symmetric multiprocessing enhancements
    The Windows Server 2003 family supports single or multiple CPUs that conform to the symmetric multiprocessing (SMP) standard. Using SMP, the operating system can run threads on any available processor, which makes it possible for applications to use multiple processors when additional processing power is required to increase the capability of a system. New features include SMP locking performance, improved registry performance, and increased Terminal server sessions.
  • Network Load Balancing
    Previously known as Windows NT Load Balancing Service (WLBS), Network Load Balancing distributes incoming TCP/IP traffic between multiple servers. Your clustered applications, especially Web server applications, can handle more traffic and provide higher availability and faster response times.
  • ****Server clusters (Windows Server 2003, Enterprise Edition and Windows Server 2003, Datacenter Edition only)
    Server clusters provide high availability, scalability, and manageability for important resources and applications. Multiple servers (nodes) in a cluster remain in constant communication. If one of the nodes in the cluster is unavailable due to failure or maintenance, another node immediately begins providing service (a process known as failover). Users who access the cluster are constantly connected to server-based resources. For more information, see Windows Clustering.
  • Enterprise Memory Architecture (Windows Server 2003, Enterprise Edition and Windows Server 2003, Datacenter Edition, not including 64-bit versions)
    With Enterprise Memory Architecture, you can run applications that take advantage of large amounts of physical memory on Windows Server 2003, Enterprise Edition. Using applications that are written with the Address Windowing Extensions (AWE) API, you can map more physical memory into the applications' virtual address memory space for improved performance. For systems with 2 GB to 4 GB of memory, you can also use application memory tuning, also known as 4-gigabyte tuning (4GT). This enables you to provide up to 3 GB of your virtual address memory space to applications (by providing less memory to the operating system).

New and updated features since Windows 2000

The Windows Server 2003 family offers the following improvements (in comparison to Windows 2000) that help provide increased levels of server scalability:

  • Internet Information Services 6.0
    Internet Information Services (IIS) 6.0 is a full-featured Web server that provides the foundation for the Windows Server 2003 family and existing Web applications and Web services. IIS 6.0 offers dedicated application mode, which runs all application code in an isolated environment. IIS 6.0 also supports Web gardens, in which equivalent processes on a computer each receive a share of the requests that are normally served by a single process, achieving better multiprocessor scalability. Note
    • By default, IIS is not installed with new installations of Windows Server 2003, Standard Edition; Windows Server 2003, Enterprise Edition; and Windows Server 2003, Datacenter Edition. You can add it by using the Configure Your server Wizard or by using Add or Remove Programs.
  • Network Load Balancing enhancements
    Several improvements have been made to Network Load Balancing in this release:

    • Network Load Balancing can now be bound to multiple network adapters, so that you can configure multiple independent clusters on each host. For more information about virtual clusters, see Virtual clusters.

    • Network Load Balancing uses Internet Group Management Protocol (IGMP) support for limiting switch flooding, so that traffic intended for a Network Load Balancing cluster passes through only those ports that serve the cluster hosts and not through all switch ports.

    • With Network Load Balancing Manager, you can create new Network Load Balancing clusters, and you can configure and manage clusters and all the cluster's hosts from a single remote or local computer.