Here are a few points of clarification: - External hardware Http load balancing is setup using sticky sessions - mod_jk is setup using sticky sessions - there is no session state replication (a lost Tomcat/Jboss instance requires a user to log back on) - the tomcat/Jboss instances are on seperate machines
This is more or less your example no 1 below. If you take the following example: Http request 1 is sent to A1 by the ext LB this request may go to T1. Then http request 2 is sent to A2 this request may also go to T1. Now T1 has double the load of T2 which is currently at zero. What I am trying to work out in my is: 1. Does this matter or should it somehow be biased? 2. Will things be evened out as the no of requests increase? 3. How will it scale when adding non-even nos. of Tomcats to Apaches? 4. How to represent this in mathematical terms? Ralph Einfeldt wrote: > To me it's not quite clear what you are doing exacly. > > I see three option to use an externl loadbalancer. > Which one is the one you use ? > > - use mod_jk with sticky sessions. > - Setup two apaches with a mod_jk. > - Setup loadbalancing for mod_jk. > - Setup two tomcats with a unique jvmRoute. > > LB > / \ > / \ > A1 A2 > |\ /| > | \ / | > | x | > | / \ | > |/ \| > T1 T2 > > Although the last mails from Bill Barker indicate that current > implementation of mod_jk doesn't balance the load equally, this > scenario should work for you, as the external load balancer does > this already. The Loadbalancer in mod_jk is just used to route > the requests to the correct tomcat. > > - use session replication. > In this scenario each instance of tomcat has a copy of the session > data, so it doesn't matter which receives the request. > In this case you can omit apache and mod_jk and use tomcat native. > > LB > / \ > / \ > A1 A2 > | | > | | > T1---T2 > > - use a load balancer that supports sticky sessions > (url and cookie based sessions) > > In this case you can treat each tomcat as a stand alone > server. > > LB > / \ > / \ > A1 A2 > | | > | | > T1 T2 > > > -----Original Message----- > > From: Peter Anning [mailto:[EMAIL PROTECTED] > > Sent: Tuesday, August 26, 2003 5:14 PM > > To: Tomcat Users List > > Subject: Re: mod_jk load balancing with multiple apache servers > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
