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From: "David Brown" <david@davidwbrown.name>
Subject: RE: Tomcat and Apache mod_jk For Failover
To: "Tomcat Users List" <users@tomcat.apache.org>
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Message-Id: <1202334363.19874@davidwbrown.name>
In-Reply-To: <BLU104-W53891CE3E1B51F4967BE8DBF2D0@phx.gbl>
Date: Wed, 06 Feb 2008 15:46:03 -0600 (CST)

Hello, webmin has the HA monitor module that helps with setup and config on Linux boxes.

James Ellis wrote ..
> 
> Rainer,
>  
> Thanks for your feedback:
>  
> > Also: if you do clustering, you might be concerned about availability. > The
> load balancer itself is a single point of failure, unless you > implement some
> redunfdancy in that layer to.
>  
> That's another concern I have.  I was thinking of Linux HA - although I have never
> used it so I'm hoping its not that difficult to setup/administer.
>  
> > Date: Wed, 6 Feb 2008 22:33:39 +0100> From: rainer.jung@kippdata.de> To: users@tomcat.apache.org>
> Subject: Re: Tomcat and Apache mod_jk For Failover> > Hi James,> > James Ellis
> schrieb:> > I am trying to set up a cluster of Tomcat servers where they> > replicate
> session btwn the tomcat servers. My questions are:> > > > 1) For failover, if I
> am using apache/mod_jk as a load balancer, will> > it automatically detect if one
> of the members in the cluster is down> > and not route requests to it?> > Yes,
> if the problem is formally detectable, e.g. network problems, no > responses etc.
> What problems get detected depends much on configuration. > Have a look at> > http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html>
> > and for a complete list of attributes at> > http://tomcat.apache.org/connectors-doc/reference/workers.html>
> > You should configure a status worker, such that you can inspect your > load balancer
> status via a HTML GUI. See> > http://tomcat.apache.org/connectors-doc/reference/status.html>
> > > 2) Are there any issues assoicated with SSL and apache as the load> > balancer?>
> > Not that I'm aware of, but maybe I don't get the point. Usually you > terminate
> SSL on httpd and then simply use AJP13 as a protocol between > mod_jk and Tomcat.
> More or less it's the only protocol mod_jk speaks.> > The module then automatically
> tells Tomcat, if the original request was > coming in via http or https.> > > 3)
> Are there performance gains by using Apache/mod_jk as the load> > balancer, or
> should I just use another Tomcat instance and the> > "balancer" web app?> > More
> often performance is not the key decision criterion. I assume the > balancer webapp
> is not really production grade, but others might correct > me here.> > To choose
> the right load balancing solution, you have to decide which > people should administer
> and troubleshoot it, and which technology best > fits their skills (network appliances,
> Apache web server with mod_jk, ...).> > Also: if you do clustering, you might be
> concerned about availability. > The load balancer itself is a single point of failure,
> unless you > implement some redunfdancy in that layer to.> > > Thanks,Jim> > Regaqrds,>
> > Rainer> > --------------------------------------------------------------------->
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