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Posted to users@tomcat.apache.org by James Ellis <el...@hotmail.com> on 2008/02/06 19:57:11 UTC
Tomcat and Apache mod_jk For Failover
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?
2) Are there any issues assoicated with SSL and apache as the load balancer?
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?
Thanks,Jim
RE: Tomcat and Apache mod_jk For Failover
Posted by David Brown <da...@davidwbrown.name>.
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> > --------------------------------------------------------------------->
> To start a new topic, e-mail: users@tomcat.apache.org> To unsubscribe, e-mail:
> users-unsubscribe@tomcat.apache.org> For additional commands, e-mail: users-help@tomcat.apache.org>
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RE: Tomcat and Apache mod_jk For Failover
Posted by James Ellis <el...@hotmail.com>.
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> > ---------------------------------------------------------------------> To start a new topic, e-mail: users@tomcat.apache.org> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org> For additional commands, e-mail: users-help@tomcat.apache.org>
Re: Tomcat and Apache mod_jk For Failover
Posted by Rainer Jung <ra...@kippdata.de>.
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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