How alarms work

Alarms allow you to continuously monitor the web services running on the GAS for signs of failure and to measure performance.

Monitoring of services depends on a predefined set of alarms. Alarms are grouped into two types:
  • Counting alarms report on failures such as DVM crashes, failures to start or connect, and request/response errors. Monitoring of these alarms allow you to detect configuration or network issues.
  • Timer alarms report the time taken to start a DVM and process requests, and measure request frequencies in averages and real time, for example AVG_REQUEST_TIME and REAL_REQUEST_TIME. Monitoring of these alarms allow you to detect network issues.
You can configure alarms for either the session or the service. Typically, you would configure DVM_NOT_STARTED and DVM_NOT_CONNECTED alarms for each service.
Tip:

You can configure an alarm on a service even if it is not running. The configuration takes effect the next time the service is started.

Alarm thresholds

Each alarm has a default threshold. The GAS raises an alarm if the threshold is met or exceeded.
  • For counting alarms, this threshold is typically a single (1) occurrence.
  • For timer alarms, this threshold is typically one (1) second.

You may need to modify alarm thresholds in order to better represent conditions in your network. For instance, if you know you system is slow, you may decide to raise a DVM_NOT_CONNECTED alarm after 5 attempts, instead of the default one attempt.

There are considerations for setting thresholds. Setting a threshold too low can create complacency, as you attempt to manage a large volume of monitoring data on a system that shows no signs of any disruption or issues. Setting a threshold too high reduces the volume of monitoring data collected and ultimately fetched for analysis; however, it can also result in not being alerted of potential problems in a timely manner.

When an alarm is raised

When the GAS raises an alarm, it writes the event to a monitoring data (.dat) file for the session. The monitoring data written to the file specifies which alarm was raised, along with details of the event. To receive an email alert, configure the GAS to send you notification when an alarm is raised. For details, see Alert script example.

To better understand what is happening, you may need to raise the monitoring level of the service to gather more information.

To analyze the monitoring data, and to debug potential issues, you fetch the data to a file for transfer to a Microsoft® Excel™ spreadsheet, or to a third party monitoring system where you can process and graph the data.