Application Center uses Health Monitor to create two default data groups: Synchronized Monitors and Non-Synchronized Monitors. The contents of the Synchronized Monitors data group synchronize across all of a cluster's servers. Because a monitor must reside on a server to be functional, this synchronization can save much duplication of effort. Synchronization within a cluster occurs from the controller to every other cluster member, so you should create the Synchronized Monitors data group on a cluster controller. Alternatively, a monitor might apply to only one server. You should create such a monitor in the Non-Synchronized Monitors data group on the server, and that monitor will be functional on only that server.
When Application Center installs Health Monitor, it populates the Synchronized Monitors container with default monitors for basic monitoring of the cluster members (e.g., processor and memory utilization, HTTP response times) and information about the cluster service. Health Monitor also creates sample monitors for monitoring Application Center and additional products (e.g., Microsoft SQL Server, Microsoft BizTalk Server 2000, Microsoft Commerce Server 2000) and for monitoring such items as COM+ applications and Web sites.
Figure 1, page 10, shows the Health Monitor interface. You can see the hierarchical relationship between the threshold, data groups, and server: The thresholds in the top-right pane relate to the Cluster Service data collector. This data collector is in the Application Center Monitors data group, which is on the homeap server.
You now understand the basic steps of creating a monitor. Let's take a look at how Application Center can help you manage your clusters.
Default Monitors
Application Center configures several default monitors, which contain default data collectors, in the Synchronized Monitors container, although not all the data collectors are enabled by default. In Figure 1, you can see the default Synchronized Monitors. The gray circle icon with the downward-pointing white arrow, which you see over some of the data collectors in the left pane, denotes a disabled data collector. To enable a data collector, right-click the icon and choose All Tasks. On the resulting menu, click Disabled to clear the check box. Let's look closely at one of these default monitors.
Notice that the Synchronization Session Errors data collector contains four thresholds. The first threshold checks the value of the error code that WMI reports. If the value is anything other that 0, a failure has occurred in WMI and Health Monitor considers this error critical. This threshold is standard for any data collector that uses WMI.
Figure 2 shows the properties of the Synchronization Session Errors data collector. Because the data collector uses WMI, its properties show the WMI namespace and class. The collected data applies to Application Center replication sessions and resides in the Application Center namespace. The Properties window shows all the properties that the data collector can monitor, and a selected check box indicates a monitored (i.e., collected) property. This data collector is monitoring four properties (i.e., EventId, ReplicationJobID, Status Message, and Type), one for each threshold, but you can set multiple thresholds for one collected property.
The WMI Query Language (WQL) event query, in the lower half of the dialog box, isolates pertinent data. This query can apply to an intrinsic event, which lets you identify a generic creation, deletion, modification, or operation event with an instance, class, or namespace. If you want to create a more specific query, you can create an extrinsic event, which lets you define an event specific to your needs. In Figure 2, the monitor is configured to respond to the generation of specific events rather than any event, so the monitor uses an extrinsic query. As you can see, the data collector is specifically interested in event IDs 5037 (successful completion of synchronization) and 5043 (successful integration of synchronization changes), and the synchronization's Type value is 1, which indicates a failure. Each threshold in the data collector responds to one of these events. The event IDs reset the state to OK, and the Type changes the state to critical. The configured action at the data-collector level is Email an administrator. No default actions are configured at the data-group level for any monitors in the Application Center Monitors data group. The Application Center Log Monitors data group contains collectors that retrieve information about Application Center's logging functionality. The Microsoft Data Engine (MSDE) 8.0 stores the logged information, and these data collectors and thresholds ensure that the logging services start and log correctly and monitor the size of the database.
The remaining data collectors in the Application Center Log Monitors data group perform the following functions:
- check for the successful starting of the cluster service
- check for failure of Health Monitor or Request Forwarding (i.e., the ability of Application Center clusters to return a client to a previously configured cluster node, if necessary)
- check whether a server is reporting event ID 4016, which indicates that the server is offline because of the drain process (which permits connected clients to remain online for a period of time to finish a task but refuses new client connections)
The software automatically creates three more data groups: Online/Offline Monitors, System Monitors, and Web Site Monitors.
Online/Offline Monitors. The Online/Offline Monitors data group contains one data collector and one threshold that uses WMI to determine whether the Web service has started. If the Web service hasn't started, the threshold puts the monitor into a critical state. The action for the data collector is to email an administrator. The Offline/Online Monitors data group has an additional action, which is to take the server offline in the event of a critical state and online for an OK state. Therefore, any data collector placed in this group with a threshold configured to change the state of the monitor to critical will automatically take the affected server offline.
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