Request forwarding manages session state among IIS servers
Editor's Note: Each month, this column discusses various aspects of the advanced administration of e-business sites. This month's column examines Microsoft Application Center 2000—a Microsoft .NET server that handles the management and deployment of servers in a Web farm.
Application Center is a set of tools and services that lets you manage a farm of IIS Web servers as if they were one machine. This concept of grouping servers to facilitate managing them as a whole is called an Application Center server cluster. With Application Center, you can create clusters or add member servers to and remove them from existing clusters. When you've defined an Application Center server cluster, you can automatically deploy new content to the cluster group as a whole, configure load balancing, and monitor cluster performance.
Application Center Installation and Configuration
The recommended server configuration for Application Center is a Pentium-class 400MHz or faster processor, 256MB of RAM, and ample disk space (Application Center requires about 100MB plus hosted data files). If you want to take advantage of Network Load Balancing (NLB), you need to run Windows 2000 Advanced Server and have two NICs per server.
At the time of publication, Application Center is in beta 2, and the installation and configuration procedures are likely to change. In addition, Microsoft has yet to document the installation procedures that involve NLB.
NLB is one of the Win2K clustering features and is available only in Win2K AS and Win2K Datacenter Server. NLB uses one virtual IP address to cluster applications on multiple servers, which lets you create port rules based on application port numbers and load balancing based on an evenly distributed load (the default setting) or a manually configured distribution matrix. Running NLB with Application Center requires two NICs per server—one NIC for the client-to-cluster traffic and a dedicated NIC for traffic specific to the computer. Configure only one adapter per server with NLB. Here are a few hints to make NLB configuration as painless as possible:
- Install NICs on separate subnets to minimize network traffic.
- Add the virtual IP address as an additional address in the NICs' Internet Protocol (TCP/IP) properties.
- Set Cluster Parameters and Port Rules identically on all cluster hosts, but make the Host Parameters unique for each server.
- Ensure that all ports for a given application are open in Port Rules (e.g., FTP uses ports 20, 21, and 1024 through 65535).
- Follow the NLB Best Practices sheet in Win2K AS Help.
When NLB is up and running, Application Center installation is easy. The beta 2 installation requires four steps that Microsoft will most likely incorporate into the release to manufacturing (RTM) version. These four installation steps are
- Service Pack 1 (SP1)
- Pre-SP2 hotfixes
- Application Center components
- Microsoft Health Monitor 2.1 components
When you've installed Application Center on each server that's to be a cluster member, you need to set up the cluster. Follow these steps to configure the Application Center cluster for Web site clustering:
- Open the Microsoft Management Console (MMC) Application Center snap-in, right-click Application Center, and select Connect As.
- On the Connect to Server dialog box, enter the name of the server you want to be the controller for the cluster. Select the Manage cluster for this server option.
- On the New Server dialog box, select the Create a new cluster option, then click OK to start the New Cluster Wizard. Click Next.
- The wizard analyzes your server configuration. When analysis is complete, click Next.
- Enter the cluster name and a description (optional). Click Next.
- Select the type of cluster you want to deploy. Select the Web cluster option, as Figure 1 shows, then click Next.
- The wizard now detects your NLB settings. You can let the wizard set the optimal NLB settings, or you can use the existing settings. Microsoft recommends that you let Application Center reconfigure your NLB settings, but this reconfiguration could break NLB if you have anything other than the default configuration (e.g., if you use Multicast). Select the option that best fits your needs, then click Next.
- On the Monitoring Notifications screen of the wizard, which Figure 2 shows, enter the email address and mail server name that Application Center will use to notify you if the cluster encounters a failure. Click Next, then click Finish. Application Center will create the cluster.
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