Author: schultz
Date: Wed Jan 30 21:48:04 2019
New Revision: 1852557
URL: http://svn.apache.org/viewvc?rev=1852557&view=rev
Log:
Remove out-dated warning about BackupManager.
Clarify language.
Modified:
tomcat/trunk/webapps/docs/cluster-howto.xml
Modified: tomcat/trunk/webapps/docs/cluster-howto.xml
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/docs/cluster-howto.xml?rev=1852557&r1=1852556&r2=1852557&view=diff
==============================================================================
--- tomcat/trunk/webapps/docs/cluster-howto.xml (original)
+++ tomcat/trunk/webapps/docs/cluster-howto.xml Wed Jan 30 21:48:04 2019
@@ -49,11 +49,15 @@
</p>
<p>
Using the above configuration will enable all-to-all session replication
- using the <code>DeltaManager</code> to replicate session deltas. By
all-to-all we mean that the session gets replicated to all the other
- nodes in the cluster. This works great for smaller cluster but we don't
recommend it for larger clusters(a lot of Tomcat nodes).
- Also when using the delta manager it will replicate to all nodes, even
nodes that don't have the application deployed.<br/>
- To get around this problem, you'll want to use the BackupManager. This
manager only replicates the session data to one backup
- node, and only to nodes that have the application deployed. Downside of
the BackupManager: not quite as battle tested as the delta manager.
+ using the <code>DeltaManager</code> to replicate session deltas. By
all-to-all, we mean that <i>every</i>
+ session gets replicated to <i>all the other nodes</i> in the cluster.
+ This works great for smaller clusters, but we don't recommend it for
larger clusters — more than 4 nodes or so.
+ Also, when using the DeltaManager, Tomcat will replicate sessions to
<i>all</i> nodes,
+ <i>even nodes that don't have the application deployed</i>.<br/>
+ To get around these problem, you'll want to use the
<code>BackupManager</code>. The <code>BackupManager</code>
+ only replicates the session data to <i>one</i> backup node, and only to
nodes that have the application deployed.
+ Once you have a simple cluster running with the <code>DeltaManager</code>,
you will probably want to
+ migrate to the <code>BackupManager</code> as you increase the number of
nodes in your cluster.
</p>
<p>
Here are some of the important default values:
@@ -108,7 +112,7 @@
<ClusterListener
className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>]]></source>
- <p>Will cover this section in more detail later in this document.</p>
+ <p>We will cover this section in more detail later in this document.</p>
</section>
<section name="Security">
@@ -163,12 +167,15 @@ should be completed:</p>
<li>Using in-memory-replication, using the SimpleTcpCluster that ships with
Tomcat (lib/catalina-tribes.jar + lib/catalina-ha.jar)</li>
</ol>
-<p>In this release of session replication, Tomcat can perform an all-to-all
replication of session state using the <code>DeltaManager</code> or
+<p>Tomcat can perform an all-to-all replication of session state using the
<code>DeltaManager</code> or
perform backup replication to only one node using the
<code>BackupManager</code>.
- The all-to-all replication is an algorithm that is only efficient when the
clusters are small. For larger clusters, to use
- a primary-secondary session replication where the session will only be
stored at one backup server simply setup the BackupManager. <br/>
+ The all-to-all replication is an algorithm that is only efficient when the
clusters are small. For larger clusters, you
+ should use the BackupManager to use a primary-secondary session replication
strategy where the session will only be
+ stored at one backup node.<br/>
+
Currently you can use the domain worker attribute (mod_jk > 1.2.8) to
build cluster partitions
- with the potential of having a more scalable cluster solution with the
DeltaManager(you'll need to configure the domain interceptor for this).
+ with the potential of having a more scalable cluster solution with the
DeltaManager
+ (you'll need to configure the domain interceptor for this).
In order to keep the network traffic down in an all-to-all environment, you
can split your cluster
into smaller groups. This can be easily achieved by using different
multicast addresses for the different groups.
A very simple setup would look like this:
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