[jboss-cvs] JBossAS SVN: r84592 - projects/docs/community/5/Clustering_Guide/en-US.
jboss-cvs-commits at lists.jboss.org
jboss-cvs-commits at lists.jboss.org
Sat Feb 21 09:24:29 EST 2009
Author: bstansberry at jboss.com
Date: 2009-02-21 09:24:29 -0500 (Sat, 21 Feb 2009)
New Revision: 84592
Modified:
projects/docs/community/5/Clustering_Guide/en-US/Clustering_Guide_Introduction.xml
Log:
General edits
Modified: projects/docs/community/5/Clustering_Guide/en-US/Clustering_Guide_Introduction.xml
===================================================================
--- projects/docs/community/5/Clustering_Guide/en-US/Clustering_Guide_Introduction.xml 2009-02-21 14:11:56 UTC (rev 84591)
+++ projects/docs/community/5/Clustering_Guide/en-US/Clustering_Guide_Introduction.xml 2009-02-21 14:24:29 UTC (rev 84592)
@@ -395,8 +395,8 @@
<section id="clustering-quickstart-ejbsessions">
<title>EJB Session Bean Clustering Quick Start</title>
<para>JBoss AS supports clustered EJB session beans, whereby
- requests for a bean are balanced across the cluster, and, for
- stateful beans, a backup copy of bean state is maintained on one
+ requests for a bean are balanced across the cluster. For
+ stateful beans a backup copy of bean state is maintained on one
or more cluster nodes, providing high availability in case the
node handling a particular session fails or is shut down. Clustering
of both EJB2 and EJB3 beans is supported.
@@ -446,6 +446,7 @@
of database reads. You should always load test your application
with second level caching enabled and disabled to see whether
it has a beneficial impact on your particular application.</para>
+
<para>If you use more than one JBoss AS instance to run your
JPA/Hibernate application and you use second level caching, you must
use a cluster-aware cache. Otherwise a cache on server A will still
@@ -496,6 +497,15 @@
<para>See <xref linkend="clustering-entity"/> for more advanced
configuration options and details on how to configure the same
thing for a non-JPA Hibernate application.</para>
+
+ <note><para>Clustering can add significant overhead to a JPA/Hibernate
+ second level cache, so don't assume that just because second level
+ caching adds a benefit to a non-clustered application that it will be
+ beneficial to a clustered application. Even if clustered second level
+ caching is beneficial overall, caching of more frequently modified
+ entity types may be beneficial in a non-clustered scenario but not in
+ a clustered one. <emphasis>Always</emphasis> load test your application.
+ </para></note>
</section>
</section>
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