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From Felix Schumacher <felix.schumac...@internetallee.de>
Subject Re: pure tomcat failover (no loadbalacing)
Date Wed, 27 Apr 2011 19:55:03 GMT
Am Mittwoch, den 27.04.2011, 19:20 +0100 schrieb Guillaume Favier:
> Felix,
> 
> Dis you check my workaround ?
> 
> 
> On Wed, Apr 27, 2011 at 7:01 PM, Felix Schumacher <
> felix.schumacher@internetallee.de> wrote:
> 
> > Am Mittwoch, den 27.04.2011, 10:21 +0200 schrieb Felix Schumacher:
> > > On Wed, 27 Apr 2011 09:58:45 +0200, Felix Schumacher wrote:
> > > > On Tue, 26 Apr 2011 21:24:16 +0100, Guillaume Favier wrote:
> > > >> Thanks for your answer Felix,
> > > > Well, after rethinking my original answer, I think you will have to
> > > > define two clusters:
> > > >
> > > >   worker.list=cluster1,cluster2
> > > >
> > >  ...
> > > >   worker.c2t2.type=ajp13
> > > >   worker.c2t2.host=localhost
> > > >   worker.c2t2.port=9002
> > > >   worker.c2t2.redirect=c1t1
> > >  Aargh, this should be
> > >    worker.c2t2.redirect=c2t1
> > Ok, last correction. redirect takes the name of the jvmRoute, not that
> > of the worker. So those two configuration entries should be
> >
> > worker.c2t2.redirect=tomcat1
> > worker.c1t1.redirect=tomcat2
> >
> >
> argh you're right, but with my work around you can avoid dealing with the
> route, it is a bit more scalable.
> 
> I implement a workaround by dealing with lbfactor :
> worker.c1t1.lbfactor=100
> worker.c1t1.redirect=cluster1
> 
> worker.c1t2.lbfactor=1
> worker.c1t2.redirect=cluster1
> #worker.c1t2.activation=disabled
> 
> It is very unlikely that i get 100 request on one server.
> This does looks good but a pretty complex configuration if we move up to
> three server. And complexity will increase with the number of server.
> Seems that load balancing is easier than failover.
I don't think lbfactor is the right solution for your problem, but I
haven't checked it. I think your setup will pass 100 requests to worker
c1t1 and then 1 request to worker c1t2 (probably simplified it quite a
lot). That will trigger your servlets from your "failover" instance,
which you wanted to circumvent.

As stated in my correction above, redirect takes the name of the
jvmRoute and I doubt, that your tomcat instance is called cluster1, so
that statement will be wrong.

You are right that loadbalancing is simpler than my example with two
clusters, but that is because your original requirement were more
complex then simple loadbalancing.

If you have the memory resources for simple loadbalancing I would go for
it.

Regards
 Felix
> 
> gui
> 
> 
> 
> 
> > Regards
> >  Felix
> > >
> > >  Bye
> > >   Felix
> > > >
> > > > You will have to set "jvmRoute" in your tomcats to "tomcat1" and
> > > > "tomcat2".
> > > >
> > > > To mount your webapps, you can use
> > > >
> > > >   JkMount /ABC* cluster1
> > > >   JkMount /DEF* cluster2
> > > >
> > > > Regards
> > > >  Felix
> > > >
> > > >>
> > > >>
> > > >> On Tue, Apr 26, 2011 at 8:36 PM, Felix Schumacher <
> > > >> felix.schumacher@internetallee.de> wrote:
> > > >>
> > > >>> On Mon, 25 Apr 2011 09:40:59 +0100, Guillaume Favier wrote:
> > > >>>
> > > >>>> Hi,
> > > >>>>
> > > >>>> I have 2 tomcat 5.5 server. Each of them handling a set (50+)
of
> > > >>>> third
> > > >>>> party
> > > >>>> webapps name /ABC* and /DEF*.
> > > >>>> Each of these webapp is quite memory consumming when started
(more
> > > >>>> than
> > > >>>> 300M).
> > > >>>> I would like all connection to ABC* webapps be handled by
tomcat
> > > >>>> server 1,
> > > >>>> and connection to webapps DEF* to be handled by tomcat server
2.
> > > >>>>
> > > >>>> My objectives are :
> > > >>>> * server 1 to be failover of server2 and server2 failover
of
> > > >>>> server1.
> > > >>>> * any webapp should be instanciate on only one server otherwise
it
> > > >>>> might
> > > >>>> trigger a memory overload
> > > >>>>
> > > >>>> So I set up my httpd.conf as is :
> > > >>>>
> > > >>>> JkWorkersFile "conf/worker.properties"
> > > >>>>  JkOptions +ForwardKeySize +ForwardURICompat
> > > >>>>
> > > >>>>
> > > >>>> and my worker.properties as is :
> > > >>>>
> > > >>>> worker.list = failover
> > > >>>>
> > > >>>> # ------------------------
> > > >>>> # template
> > > >>>> # ------------------------
> > > >>>> worker.template.type=ajp13
> > > >>>> worker.template.lbfactor=1
> > > >>>> worker.template.connection_pool_timeout=600
> > > >>>> worker.template.socket_timeout=1000
> > > >>>> worker.template.fail_on_status=500
> > > >>>>
> > > >>>> # ------------------------
> > > >>>> # tomcat1
> > > >>>> # ------------------------
> > > >>>> worker.tomcat1.reference=worker.template
> > > >>>> worker.tomcat1.port=9001
> > > >>>> worker.tomcat1.host=localhost
> > > >>>> worker.tomcat1.mount=/ABC* /ABC/*
> > > >>>>  worker.tomcat1.redirect=failover
> > > >>>>
> > > >>>> # ------------------------
> > > >>>> # tomcat2
> > > >>>> # ------------------------
> > > >>>> worker.tomcat2.reference=worker.template
> > > >>>> worker.tomcat2.port=9002
> > > >>>> worker.tomcat2.host=localhost
> > > >>>> worker.tomcat1.mount=/DEF* /DEF/*
> > > >>>>
> > > >>>               ^ is this correct or a typo?
> > > >>
> > > >>
> > > >> Sorry for the typo, you're right : it is in fact :
> > > >> worker.tomcat2.mount=/DEF* /DEF/*
> > > >>
> > > >>
> > > >>>  worker.tomcat2.redirect=failover
> > > >>>>
> > > >>>>
> > > >>>> # ------------------------
> > > >>>> # failover
> > > >>>> # ------------------------
> > > >>>> worker.failover.type=lb
> > > >>>> worker.failover.balance_workers=tomcat1,tomcat2
> > > >>>>
> > > >>>> The jvmroute is set in both server.xml.
> > > >>>>
> > > >>>> Previously I had put the jkMount directive in httpd.conf,
but I
> > > >>>> could'nt
> > > >>>> make the failover work. So I move it in the worker.properties.
> > > >>>> Tomcat doesn't seem to take into account the jkmount directive
> > > >>>> from the
> > > >>>> worker.properties : a webapp is started indifrently on any
server.
> > > >>>>
> > > >>> Tomcat starts all webapps it can find, not only those you specified
> > > >>> by a jk
> > > >>> mount. Servlets will
> > > >>> only start, if you specify a startup order, or trigger a request
to
> > > >>> a
> > > >>> servlet.
> > > >>>
> > > >>>
> > > >> Ok, maybe I should clarify that :
> > > >> 1) tomcat starts all webapps
> > > >> 2) when a users connect to a specific webapp all objects are
> > > >> instanciate and
> > > >> therefore the memory footprint drasticaly increase.
> > > >> I want to work on the second point : a webapp should be instanciate
> > > >> only on
> > > >> one server.
> > > >>
> > > >>
> > > >>
> > > >>> So I don't think it is possible to prevent a webapp from starting
> > > >>> in the
> > > >>> "failover" tomcat. But it
> > > >>> should be possible to limit its memory footprint.
> > > >>>
> > > >>
> > > >> I have done some optimisation here and already removed all shared
> > > >> classes,
> > > >> jar, etc...
> > > >>
> > > >>
> > > >>> That said, I find it strange, that you define a special failover
> > > >>> worker
> > > >>> instead of a direct redirect like
> > > >>>
> > > >>> worker.tomcat1.redirect=tomcat2
> > > >>> worker.tomcat2.redirect=tomcat1
> > > >>>
> > > >>>
> > > >> But that would mean (solution already tested) : I have to declare
it
> > > >> in the
> > > >> worker list, so when a server fail httpd will continue to try to
> > > >> contact it
> > > >> instead of contacting the failover worker and find a another worker
> > > >> -> even if it works it would only work for 2 servers not for 3.
> > > >>
> > > >> thanks
> > > >> gui
> > > >
> > > >
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> > >
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> >
> >
> >
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> >



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