Scenario: Installing a Team Foundation Server Farm (High Availability)
You might add an application-tier server to an existing deployment of Visual Studio Team Foundation Server for any of the following reasons:
You want to build redundancy into your deployment of Team Foundation Server.
You want your deployment of Team Foundation Server to run faster.
You want to restore an application-tier server that has failed.
You want to move an application tier to a different server.
Redundancy and Performance
In earlier versions of Team Foundation Server, you could run only the data tier on a SQL Server cluster. This limitation meant that you could enhance scalability for only part of your deployment of Team Foundation Server: the data tier. By using the Application-tier Only Configuration wizard, you can enhance the availability, scalability, and performance of your application tier also.
To benefit from multiple application-tier servers, you should ensure that your initial deployment of Team Foundation Server includes the following characteristics:
The application tier and the configuration database are installed on separate servers.
You used a domain account for the Team Foundation Server service account (TFSSERVICE).
Network Load Balancing (NLB) is deployed.
You use NLB to create a cluster of Web servers that appear as a single logical Web service. This procedure is separate from the Application-tier Only Configuration wizard. For more information about how to set up NLB, see the following page on the Microsoft Web site: Network Load Balancing.
If you want to connect to an NLB cluster from a client that is running on one of the application-tier servers in the cluster, you should connect using localhost as the name of the server, instead of the Domain Name System (DNS) name for the load balancer. By default, Internet Information Services (IIS) prevents you from connecting to an NLB cluster from any server in the cluster, unless you use localhost as the name of the cluster.
If you create an NLB cluster, you do not need to use a SQL Server cluster for your configuration database or any team project collection. For the purposes of performance, scalability, and availability, any SQL Server cluster that you might deploy is independent of the NLB cluster.
Disaster Recovery and Hardware Upgrade
If you have a backup of your configuration database and your application tier has a hardware failure, you can use the Application-tier Only Configuration wizard to restore the application tier.
You can also move your application tier with the Application-tier Only Configuration wizard. Although no particular architecture is required to move an application tier, you must have access to the configuration database for the deployment.