Performance counters provide important information in the tuning phase for a new cluster. Once the cluster is tuned, a subset of counters can be used to monitor ongoing stability and performance. There are additional counters that might be required when investigating an issue on the cluster.

Customers often ask about the impact to the cluster when monitoring performance counters. Performance counters are very lightweight and are updated in memory (whether they are monitored or not). Monitoring is also lightweight as long as a suitable sampling time is used. A sampling time of one minute should be sufficient in most cases. However, continuous sampling consumes large amounts of disk space. Therefore it is suggested that the monitoring tool be setup using a circular log with the option to overwrite older logs. Set the log size to give the system administration team time to investigate, or backup the log when an alert occurs (this might take some experimentation).

It is also recommended that monitoring be done from a remote computer rather than directly from the cluster computers. Refer to the following table for information on each counter. The counters can be used to investigate the most frequent bottlenecks.

The mrIWeb and mrIEngWS cluster monitoring average response time counters have been updated to average over the last interval rather than over the time since started. They are now PERF_AVERAGE_TIMER type counters instead of PERF_COUNTER_RAWCOUNT type counters.

Use the following recommendations when monitoring counters:

Note that the suggested alerts do not always indicate that a cluster is about to fail. The alerts do indicate a cluster that has started to perform less optimally and might impact user experience. Therefore, you might want to adjust alerts taking into account your acceptable level of temporary performance degradation and your cluster support staff availability.

For a list of all UNICOM Intelligence Web and Interviewer Session Engine counters, see the UNICOM Intelligence Developer Documentation Library under “Performance counters for the UNICOM Intelligence Interviewer Web service” and “Performance counters for the UNICOM Intelligence Interviewer Interviewer Session Engine”.

It might be useful to create performance counter templates for each of these monitoring requirements to be available (when required).

Some counters are only created when the process is created. For example, the engine counters for a particular engine are only created when the engine is created. This makes it more difficult to create a template in Microsoft Performance Monitor for a production environment. However it is possible to monitor transient counters using systems management and monitoring tools (such as IBM Tivoli or Microsoft Systems Manager).

The stability and performance of a UNICOM Intelligence cluster can vary greatly depending on the active projects. Large projects with lots of variable instances require more memory. Projects with complex routing require more CPU resources. Projects that use external COM objects (using CreateObject) can be impacted by the requirements of the external objects. For example, some objects might limit the number of simultaneous accesses, resulting in contention issues in a server environment. Other objects might load files into memory that increase the memory requirements. ADO objects could impact the load on the database server.

You can monitor and track many of these issues by using the performance counters (see Monitoring using performance counters). To monitor the actual performance of each project, and therefore the performance seen by the respondents (or interviewers), use the “per project” counters.

Monitoring per project performance counters becomes more of a challenge as active projects change over time. Companies with programmatic activation processes have an advantage in that the counters can be programmatically added into the monitoring tool. Alternatively, you can monitor transient counters by using tools such as IBM Tivoli or Microsoft Systems Manager.

For a list of all UNICOM Intelligence project counters, see Performance counters for UNICOM Intelligence Interviewer projects.