Load balancing best practices
When you administer the Web GUI in a load balancing environment, follows these practices to avoid problems in the cluster.
Overview
Administrative items that need special attention in a load balancing environment are as follows:
Timed tasks
Timed tasks are an essential element in the smooth running of a load balancing cluster. They ensure that all changes to files in WEBGUI_HOME/etc/configstore/ and the subdirectories are detected and loaded into the server, without the need to restart the server.
As a minimum, ensure that the timedtasks.enabled property in theserver.init file is set to true.
In most cases, the schedules that are supplied for filters and views and for other components are adequate. However, you can change the schedules to suit your specific needs. If you change the schedules in a load balancing environment, create identical schedules for the same set of components on all nodes in the cluster.
The configuration database
A load balancing cluster uses a database to hold the configuration data. Individual nodes in the cluster hold only a copy of this data, primarily for performance reasons. The master copy of the configuration data is always the one in the database.
Always ensure that the database is available before you change the configuration, especially if you edit the configuration files directly, for example if you define metrics for the gauge page. Without the database, the change to the node cannot be propagated to the other nodes. The configurations in the cluster can become inconsistent, which impairs the performance of the cluster.
Use the Web GUI itself to change the configuration. The Web GUI always checks that the database is available before you are permitted to save any changes to the configuration. This fail-safe avoids many of the potential data inconsistencies that can occur if edit the files directly.
The list of files to maintain in the database
A cluster includes a file named stores.lst that holds a list of directories whose content is to be stored in the configuration database. As supplied, the file specifies all the directories that contain information that must be synchronized across a cluster. You can add further directories to this list for other files that you want synchronized on all nodes. Subdirectories that are associated with entries in the stores.lst file are not monitored. Extra entities must be added to monitor the subdirectories.
Periodically check the stores.lst to ensure that it is fully up to date. The file is synchronized across all nodes. So any changes you make to it are automatically propagated to the other nodes.
When you edit the stores.lst file, change only thee entries that you added. Do not remove any of the supplied entries, because the operation of the cluster can be impaired.