Re: Clustering questions

Mitch Claborn wrote:
> I'm investigating to set up my first Tomcat cluster and have some questions.
>
> 1.  Using a SimpleTcpCluster, it looks like session information is
> replicated to all members of the cluster.  If all members of the cluster
> go down at once, is the session information lost?  Can a simple cluster
> be combined with a Persistent Manager to save session information if all
> members of the cluster go down at once?
>  
Tomcat 6 has two session managers
DeltaManager - all to all replication
BackupManager - primary/backup strategy
All members going down at once, means you have problem beyond
replication, and replication or storing session data will not solve
anything for you :)
> 2.  If I set up a SimpleTcpCluster, does that eliminate the need for the
> load balancer to use "sticky" sessions?
>  
yes, but it is still recommended to use sticky sessions. Many reasons why.
> 3.  Is it possible to use a PersisentManager and a shared database to
> "replicate" sessions through the database, eliminating the need for the
> clustering stuff?  I've read some posts that indicate that the
> PersistentManager writes sessions to the database at its discretion, not
> immediately.
>  
It happens periodically on a background thread.
> 4.  Has anyone used nginx as a load balancer for tomcat?  Any feedback
> on the wisdom of that?
>  
You have several options, buying an appliance or using software.
If you want software, you can use haproxy, or the apache webserver
(httpd) with mod_proxy_balancer or mod_jk

Filip

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