Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

Licensing Policy Implementation with MSCS

View products that this article applies to.


The following article discusses the licensing considerations when you deploy Microsoft Cluster Server (MSCS).

↑ Back to the top

More information

Each application vendor must determine its own licensing policies for applications running on Microsoft Cluster Server clusters.

The current policy for server application licensing provided by Microsoft applies to MSCS clusters: an application must be separately licensed for each server on which it is installed.

Per-Seat Licensing

If the customer is using per-seat Client Access Licenses (CALs) for the application, those licenses apply when a client is accessing the application on either server in the cluster.

Per-Server Licensing

If the customer is using per-server (or concurrent use) Client Access Licenses for the application, each computer in the cluster should have a sufficient number of per-server Client Access Licenses for the expected peak load of the application on that computer

For example, if both nodes of a cluster were running Microsoft SQL Server Enterprise Edition, the following licenses are needed to install a SQL Server based MSCS implementation:
  • Two fully licensed nodes of Windows NT 4.0 Server, Enterprise Edition or two licensed Windows 2000 Advanced servers.
  • Two licensed copies of SQL Server Enterprise 6.5 or 7.0. (Two SQL server licenses are required even if only one instance of the server is run at a time in active-passive mode and four licenses are required for an Active-Active configuration).
  • SQL Server Client Access Licenses (CAL’s). Both the nodes of the cluster must be licensed even if only one node at a time is being run as in active passive mode. In an environment running in per-server mode, MSCS does not transfer CAL’s from one node to the other in the event of a fail over. Separate CAL’S have to be purchased for each node even if the clients connect only to one virtual server. However, a cluster does not affect per-seat licensing.
  • Depending on the network library used for connecting to the SQL server, separate CAL’s might be needed.
    If using Named Pipes, an Windows NT 4.0/Windows 2000 CAL is needed for each client as Windows NT 4.0/Windows 2000 authenticates these connections directly.


    If using TCP/IP sockets, Windows NT 4.0/Windows 2000 CAL’s for each client are not needed because Windows NT 4.0/Windows 2000 does not authenticate these connections directly.
In a scenario where 50 users want to connect to a Virtual SQL Server using Named Pipes as default Network Library the following are the total licenses needed:
  • Two licenses each for Windows NT 4.0 / Windows 2000 Server and SQL Server.
  • 100 SQL Server Client Access Licenses (50 for each node).
  • 100 NT CAL’s (50 for each node).
In the same above scenario if we connect to an Virtual SQL Server with TCP/IP sockets as the default network library, then for 50 users we need:
  • Two licenses each for SQL Server and Windows NT 4.0 / Windows 2000 Servers.
  • 100 SQL Server Client Access licenses (50 for each node).
  • 2 Windows NT 4.0/Windows 2000 CAL’s one for each node.
NOTE: Per-server Client Access Licenses do not failover from one computer in the cluster to the other.

Cluster Server Licensing

In a Cluster Server cluster, if an application runs on both servers, or even if it only runs on one server at a time but must be installed on both servers to permit failover, the application must be licensed for both servers. Thus, MSCS is licensed per server.

Client licensing is covered under the Microsoft Windows NT Server licensing agreement.

↑ Back to the top

Keywords: kbsetup, KB175276

↑ Back to the top

Article Info
Article ID : 175276
Revision : 4
Created on : 11/1/2006
Published on : 11/1/2006
Exists online : False
Views : 405