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Chapter 6 Object Management Types : Berkeley DB Object Management

Berkeley DB Object Management
Berkeley DB OM (formerly known as Persistence-Based OM) is deprecated. Do not use this OM type in new projects. Instead use Cache Manager with backing store. Follow procedures in TIBCO BusinessEvents Installation to migrate data. You must of course configure the other features of Cache OM as well.
TIBCO BusinessEvents Express  Content relating to Berkeley DB OM is not relevant to TIBCO BusinessEvents Express edition.
As illustrated in the figure on this page, the Berkeley DB object management type persists a snapshot of the working memory for each inference agent (rule session) in the deployed system. The data for each inference agent is persisted to a data store at specified intervals.
A small cache for each inference agent ensures that currently used objects are available in memory for improved performance. You can control the size of the cache (see Caches Used for Persistence-Based Object Management in TIBCO BusinessEvents Administration).
The persistence data store uses Berkeley DB and is provided and managed by TIBCO BusinessEvents.
Persistence-based object management provides data recovery in the case of a complete system failure. When the system comes up after a system failure, TIBCO BusinessEvents restores the working memory (or memories) to the last checkpoint state. It also receives all of the previously unacknowledged messages.
Data in memory at time of failure and not yet written to disk is lost.
Use of the Berkeley DB option affects performance, because of the disk writes required. TIBCO BusinessEvents provides parameters — checkpoint interval and property cache size — to help you tune performance. You can also determine how many objects to keep in the data cache, in order to manage JVM memory usage for the application for better performance.
The persistence database can be used purely as virtual memory. You can disable recovery features if you don’t need them.
You can tune memory usage by setting the number of properties and number of events to keep in JVM memory. You can also set aside a percentage of JVM memory for use by the persistence layer.
See Cluster Tab — Berkeley DB OM Settings and Properties in TIBCO BusinessEvents Administration for details.
Fault Tolerance With Berkeley DB Manager
Fault tolerance features for Berkeley DB object management are not provided by TIBCO BusinessEvents. You can, however, implement a custom fault tolerance solution using TIBCO Rendezvous and TIBCO Hawk or third-party fault-tolerance tools. For example, you could set up two servers that each point to the same persistence data store, and you could write rules in your fault-tolerance tool to detect failure and take appropriate steps (for example, removing any lock files) when failing over to the secondary server.
If you will provide a custom fault tolerance solution, do not enable any built-in TIBCO BusinessEvents fault tolerance features. They are not used with your custom solution.

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