Adding Execution and Analytics Engines

An initial Appian installation installs three execution engines and three analytics engines.

It is possible to add up to a total of 32 execution and 32 analytics engines by defining them in the Appian CR configuration file. This spreads the process execution load over a larger number of CPUs and allows for increased process throughput and system scale.

When an execution engine is added, it is added to the list of engines that are used to start new processes. Processes are distributed across all available execution engines (so long as they have not reached the MAX_EXEC_ENGINE_LOAD threshold). Subprocesses start on the same engine as their parent.

The number of process analytics engines and process execution engines in your instance must be the same. Whenever you add a process execution engine, you must also add a process analytics engine. The process for adding engines varies depending on your site's configuration.

Add engines to an Appian installation

A standalone installation has one instance of all Appian components, which can be configured by completing the following steps.

1. Update the Appian CR configuration file.
2. Update the maximum number of report rows.

Update the Appian CR configuration file

In the analyticsExecShardCount field of the Appian CR configuration file, set the number of engine replicas:

1
2
3
spec:
  serviceManagerTopology:
    analyticsExecShardCount: <number of engine replicas>

See: Appian CRD

Increase the maximum number of report rows

After adding more engines, the maxreportrows value needs to be updated to accommodate the additional process report data generated by the new engines. If this is not updated, Appian may not be able to display or export process data correctly.

To update the maxreportrows field, do the following:

1. Calculate the new maxreportrows value with the following formula: (new engine pairs * 10,000) + current value of maxreportrows
   1. Count the number of new analytics/execution engine pairs added to the Appian CR configuration file in the previous section.
   2. Multiply this number by 10,000 and add the result to the current value of maxreportrows (the default is 30,000). For example, if you added three engine pairs, you would add 30,000 to the current 30,000 for a total of 60,000.
2. Stop Appian.

3. In the Appian CR configuration file, set maxreportrows to the value you just calculated:

   1
   2
   3
   spec:
     customProperties:
       resources.appian.analytics.application.maxreportrows: "<new maximum>"
   

4. Save and close the file.
5. Restart Appian.

Feedback