Determining server-capacity requirements

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

Determining server-capacity requirements

After you choose a cluster model, determine how to group your resources, and determine the failover policies required by each resource, you are ready to determine the hardware capacity required for each server in the cluster. This topic explains the criteria for choosing computers for use as cluster nodes.

  • Cluster storage requirements

    Each node in a cluster must have enough persistent storage capacity to store permanent copies of all applications and other resources required to run all groups. Calculate this for each node as if all of these resources in the cluster were running on that node, even if some or all of those groups run on other nodes most of the time. Plan these disk space allowances so that either node can efficiently run all resources during failover.

  • CPU requirements

    Failover can strain the CPU processing capacity of a node when it takes control of the resources from a failed node. Without proper planning, the CPU of a surviving node can be pushed beyond its practical capacity during failover, slowing response time for users. Plan your CPU capacity on each node so that it can accommodate new resources without unreasonably affecting responsiveness.

  • Random access memory (RAM) requirements

    When planning your capacity, make sure that each node in your cluster has enough RAM to run all applications that might run on either node. Also, make sure your paging files are set appropriately for each node's RAM.

    For more information about paging files, see Optimizing the paging file size and location and Change the size of the virtual memory paging file.


  • You can use the Windows DNA Performance Kit to test and tune the performance of your applications in your server cluster. For more information about the Windows DNA Performance Kit or about how to download the kit, see the Windows DNA Performance Kit link in Web Resources at the Microsoft Windows Resource Kits Web site.