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 may 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 may 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.

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 may impact user experience. Therefore, you may 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 may 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).