Thursday, May 5, 2011

WebLogic Persistent Store

The persistent store provides a built-in, high-performance storage solution for WebLogic Server subsystems and services that require persistence. 

For example -> it can store persistent JMS messages or temporarily store messages sent using the Store-and-Forward feature. 

The persistent store supports persistence to a file-based store or to a JDBC-enabled database.

Comparing File Stores and JDBC Stores

The following are some similarities and differences between file stores and JDBC stores:
The default persistent store can only be a file store. A JDBC store cannot be used as a      default persistent store.
The transaction log (TLOG) can only be stored in a default store.
Both have the same transaction semantics and guarantees. As with JDBC store writes, file store writes are guaranteed to be persisted to disk and are not simply left in an intermediate (that is, unsafe) cache.
Both have the same application interface (no difference in application code).
All things being equal, file stores generally offer better throughput than a JDBC store.
Note: If a database is running on high-end hardware with very fast disks, and WebLogic Server is running on slower hardware or with slower disks, then you may get better performance from the JDBC store.
File stores are generally easier to configure and administer, and do not require that WebLogic subsystems depend on any external component.
File stores generate no network traffic; whereas, JDBC stores will generate network traffic if the database is on a different machine from WebLogic Server.
JDBC stores may make it easier to handle failure recovery since the JDBC interface can access the database from any machine on the same network. With the file store, the disk must be shared or migrated.
Securing File Store Data
In order to properly secure file store data, you must set appropriate directory permissions on all your file store directories. If you require data encryption, you must use appropriate third-party encryption software.

Default Persistent Store

Each server instance, including the administration server, has a default persistent store that requires no configuration. The default store is a file-based store that maintains its data in a group of files in a server instance's data\store\default directory. A directory for the default store is automatically created if one does not already exist. This default store is available to subsystems that do not require explicit selection of a particular store and function best by using the system's default storage mechanism. For example, a JMS Server with no persistent store configured will use the default store for its Managed Server and will support persistent messaging.
The default store can be configured by directly manipulating the DefaultFileStoreMBean parameters. If this MBean is not defined in the domain's configuration file, then the configuration subsystem ensures that the DefaultFileStoreMBean always exists with the default values.
Also, the Administration Console enables you to change the default store parameters, such as its default directory location and Synchronous Write Policy
Default Store Location
The default store maintains its data in a data\store\default directory inside the servername subdirectory of a domain's root directory
For example, if no directory name is specified for the default file store, it defaults to:
where domainname is the root directory of your domain, typically c:\bea\user_projects\domains\domainname

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