Cluster Management Fundamentals
Once you have created a cluster and all cluster members are serving content properly, the cluster can operate without any supervision. In some cases, however, you might need to take members offline for maintenance or content deployment. In such cases, you can remove a member from load balancing without removing it from a cluster. In other cases, you might want to remove members from one cluster and add them to another cluster to counterbalance any fluctuations in cluster workload.
For example, if client workload on cluster A decreases while client workload on cluster B increases, you can use existing resources by removing members from cluster A and adding them to cluster B to support cluster B's increased workload.
Managing a cluster in Microsoft Application Center 2000 (Application Center) primarily involves monitoring the cluster to ensure maximum performance and availability. Some tasks associated with managing a cluster include adding and removing members, setting members online and offline, restarting services on members, and deploying content.
Once you have completed the New Cluster Wizard and established a cluster of one, you can add members individually by using the Add Cluster Member Wizard or from the command line. Launch this wizard from the cluster or from the server to add. By default, the first server on which you create the cluster is the cluster controller. Subsequently added members are synchronized with this controller. You can promote a different member to cluster controller at any time.
Note To use the Add Cluster Member Wizard, you must be logged on with an account that has administrative privileges on both the server to add and the cluster controller.
You must install Application Center on each member. When you add a member to a cluster, the following settings and configuration are overwritten by the controller:
Any network settings for Network Load Balancing (NLB).
Web sites, virtual directories, and Active Server Pages (ASP) applications.
Virtual sites (and their associated ISAPI filters).
Global ISAPI filters.
File system directories and files.
Exportable CAPI certificates.
Application Center monitors.
Metabase (Internet Information Services 5.0 [IIS] configuration) settings.
Added members must have the same file system structure as the controller. For example, all members of a cluster should have an NTFS file system with the same location for the system root, default Web site, and Program Files directories.
For NLB clusters, Application Center configures the NLB settings of added members to be the same as the controller. If an added member has a static dedicated IP address, Application Center retains this address. All other IP addresses on the load-balanced adapter of the added member are overwritten by cluster IP addresses on the controller.
When deploying content, deploy content to the controller only. Otherwise, this deployed content is overwritten on the next scheduled synchronization. Once you deploy content to a member, you can set this member online and promote it to cluster controller. In this manner, all members receive the deployed content when the members are synchronized with the controller.
Because deploying COM+ applications and global ISAPI filters requires the Web service to restart, Application Center does not automatically synchronize these files. To synchronize these files across a cluster, create deployments and include these files in the deployment. You can create deployments by using the New Deployment Wizard.
Application Center provides monitoring capabilities so that you can view the health, performance, and availability of clusters. By using monitoring data, you can predefine error conditions to receive alert notifications when certain thresholds are met. For example, you can configure a monitor to receive notification when a member has less than five percent of memory available.
With scripting, you can use monitoring to automate administrative tasks. In the previous example, you can run a batch or executable file when the threshold is met (the cluster member has less than five percent of memory available). This file can take action on the member, such as restarting the member, restarting specific services on the member, or setting the member offline.
Modifying Settings for NLB
During normal cluster operation, you might want to adjust certain NLB settings. For example, you can increase server weight on member A if you notice that member A has more resources available than other members. Or, you might need to add more cluster IP addresses because you have added more Web sites to the cluster. When modifying any NLB settings, first set the member offline. After making the change, set the member online.
For more information about monitoring the status of Application Center clusters, see Application Center Monitors.
For more information about using the command line to automate administrative tasks, see Command-Line Administration.
For more information about synchronizing and deploying content, see Synchronizing and Deploying Applications.
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