Creating a Cluster | Microsoft Application Center 2000 Resource Kit 2001

Through its New Cluster Wizard, Application Center achieves plug and play clustering. By using default settings that are dependent on user-supplied responses, the wizard masks the complexity of network adapter and load-balancing configuration. After you create the cluster, you can use various properties dialog boxes to modify the settings that were created by the wizard.

NOTE
Several of the choices that you make while creating a cluster will determine the role of your cluster members as well as how load balancing is managed. If you're not familiar with how load balancing works in a cluster environment, you should read Chapter 5, "Load Balancing," before you create a cluster.

Processing Activities and Their Sequence

Let's revisit the New Cluster Wizard. In addition to getting a look at the behind-the-scenes processing that occurs, you'll see which default settings are used in response to the various user-supplied responses.

Analyzing Server Configuration

The wizard analyzes the current network configuration (for example, installed software, software versions, installed network adapters, and IP address configuration) and determines how many network adapters and static IP addresses are installed on the server. The New Cluster Wizard uses this information to either stop the cluster creation process or continue by using pre-determined settings. For example, if the configuration analysis shows that NLB is already bound to a network adapter—and there are two network adapters installed—the NLB configuration is flagged as an upgrade. This, in turn, triggers a page that gives you the options of either keeping the current NLB settings or changing them.

NOTE
If there are two or more static IPs bound to the front-end adapter the wizard selects the first as the dedicated IP and the last as the cluster IP.

Cluster Name and Description

This page lets you provide a name, as well as an optional description, for the cluster. The cluster name has to conform to standard 15-character machine name validation and be a valid DNS name.

NOTE
By default, Application Center does not register the cluster name with DNS—this is left up to you.

If you choose not to provide a name, the wizard defaults to a combination of the machine name (truncated to 8 characters, if necessary) and the word "Cluster."

Cluster Type

This page allows you to identify the primary role—determined, for the most part, by the type of content and applications that are hosted—on your cluster. The following prompts are displayed on the wizard page:

General/Web cluster This cluster hosts Web sites and local COM+ applications, or will be used for general-purpose activities, such as server management or staging applications. (A fairly common server configuration is one that has COM+ components running on the same computer but out-of-process in their own COM+ processes.)
NOTE
If NLB was detected during the server configuration analysis the only available option displayed for the Cluster Type is General/Web cluster. In order to use the other options, you have to exit the wizard, unbind NLB, and then re-run the wizard.
COM+ application cluster This cluster hosts only COM+ applications that can be referenced by other servers in an Application Center Web or COM+ routing cluster, or Windows-based applications. If your intent is to host distributed COM+ components that are called by either Web or Microsoft Win32 clients, you should configure the cluster as a COM+ application cluster.
NOTE
If you choose COM+ Applications only, the next item you see will be a dialog box that asks you to identify one of two sources for client calls. The first option is applications running on other servers, such as Web servers running Active Server Pages (ASP) and Component Load Balancing (CLB). The second option is desktop COM client applications, which are typically written in a Win32 development environment such as Microsoft Visual Basic. In the case of Win32-based applications, two network adapters are required on each cluster member because, in the Win32 clients' case, NLB is used as the load-balancing technology. In scenarios where the clients are Web or routing clusters, CLB can be used. After you submit your choice, the wizard moves to the Monitoring Options page, ignoring the load balancing configuration pages that are displayed for other cluster types.
COM+ routing cluster This cluster's primary role is routing requests to a COM+ application cluster, but it can also function as a Web server cluster.
NOTE
If you want to fully exploit Application Center's CLB feature, your minimum configuration will consist of a COM+ /Web routing cluster of one member and a COM+ application cluster with two members on the back tier. A single server COM+ application cluster is fully functional for responding to Common Gateway Interface (CGI) calls, but since a single server receives all the calls, the net effect is zero component load balancing.

The information that you provide is used to determine whether NLB should be used on the cluster. NLB is used by default if either the General/Web cluster or COM+ routing cluster options are selected.

Network Load Balancing Service (NLB) Upgrade

This page is displayed only if the server configuration analysis determines that NLB is already bound to the network adapter. At this point you have the option of retaining the existing load balancing settings or reconfiguring load balancing.

NOTE
If you remove a member that was originally configured by using Keep existing settings, these settings will be lost when Application Center unbinds NLB on the member. This is done to ensure that cluster integrity—in terms of configuration and content synchronization—is preserved.

Load Balancing

If you select either General/Web cluster or COM+ routing cluster as the cluster type, the Load Balancing page is displayed. This page presents three load balancing options: Network Load Balancing (NLB), Other load balancing, or None. NLB is selected by default unless the server analysis indicated that there is only one network adapter present or that DHCP is enabled on both network adapters. If either of these conditions exists, NLB is disabled and the only available options are third-party load balancing or no load balancing.

NOTE
If an existing NLB binding with single-host (fail-over) port rules is detected, the wizard will not allow you to proceed further with cluster setup.

Load Balancing Options

The wizard identifies the network adapters that will be used when you select NLB as your load balancing option for the cluster. Application Center selects the Management traffic and load-balanced network adapters by default. You have the option of changing which adapter/IP address combination to use for the cluster's management traffic.

NOTE
By default, Application Center sets the NLB client affinity to Single if the cluster type you select is either a Web cluster or routing cluster. In most cases, this affinity setting provides the optimal load balancing for intranet-based clients. Internet clusters typically use Class C affinity. For more information about load balancing, adapter configuration, and traffic implications, see Chapter 5, "Load Balancing."

Monitoring Notifications

This page lets you set up the default notification e-mail address and the name of the SMTP server. The SMTP server defaults to the local server if SMTP is installed.

Completing the New Cluster Wizard

After the selection process is finished, the wizard launches a creation component that does some final validation checks and sets up the cluster. The wizard launches the creation component to perform the following tasks:

Checks whether all the following services and components are installed: the Cluster Service, the Replication Service, and Monitoring.
Writes the appropriate controller identification information to its configuration store.
Configures these settings: a globally unique identifier (GUID) to identify the cluster, cluster-related configuration storage paths and settings, NLB port rules for the virtual sites if NLB is used, and the default monitors.
Starts the Cluster Service and Replication Service, and then flags their startup as automatic in the Service Control Manager.
Polls the metabase to determine whether the operation was successful and sends an error message to the user interface if cluster creation fails.

Assuming that your server is set up with the necessary hardware, software, and properly configured network adapters, the entire cluster creation process only takes a few minutes.