Yep Tim is correct, BipIP is a piece of network kit which has its own
IP address, users come to that IP address and the request is served by
a web-server chosen by BigIP. BigIP can be configured to remember
which client IP addresses it has dealt with recently and stick that
user to a particular web-server (unless that web-server is dead).
So I figure it's best to let BigIP do the sticky session bit since
that's part of its core functionality. (Note that if you have a less
intelligent splitter thats no problem mod_jk will know which Tomcat a
particular user should go to, note sure how mind you - probably
because the cookies are shared ?)
I've tested my config (which is two physical servers, each running one
Apache and one Tomcat) by killing Apaches and Tomcats, the only effect
visible to the user is if you kill the Tomcat containing his session
he needs to login again (good enough for me). So once the users Tomcat
is dead the Apache (mod_jk really) handles the fact and sends Tomcat
requests over to the Tomcat instance on the other physical host.
But I'd still like to know if I can configure mod_jk to ALWAYS send
users to the local Tomcat unless thats down, in which case send them
elsewhere. Currently it seems to favour its local Tomcat but not 100%,
still works though !
Steve Quail.
______________________________ Reply Separator _________________________________
Subject: RE: Re[2]: Using Apache/Tomcat in high-traffic site
Author: Tim Sullivan <[EMAIL PROTECTED]> at internet-po
Date: 19/03/01 12:22
I'm assuming the BigIP will be setup to do session-based balancing. So
basically you have an external interface visable to the global internet...
this IP would be the IP that clients would connect to. The internal
interfaces would hit your servers. When somebody first tries to reach the
website, the BigIP (or any other session-based load balancer) creates a
'tunnel' for that entire session, and 'tunnels' that clients request to the
same box until that session disappears.
-----Original Message-----
From: Shinta Tjio [mailto:[EMAIL PROTECTED]]
Sent: Monday, March 19, 2001 11:35 AM
To: '[EMAIL PROTECTED]'
Cc: '[EMAIL PROTECTED]'; Tim Sullivan; [EMAIL PROTECTED]
Subject: RE: Re[2]: Using Apache/Tomcat in high-traffic site
We are also in the process of setting an environment like this.
I'm curious about your comment in the first paragraph.
Assuming the environment is: the loadbalancer is load balancing
Apache, there are many Apache running mod_jk, the mod_jk is
loadbalancing many Tomcat behind the Apache.
I'm not familiar with BigIP, Steve, does it forward requests
of the same sessions to the same Apache?
If your loadbalancer can't be configured to send requests
of the same sessions to the same Apache (Gavin's first question),
I don't think mod_jk will solve this. Unless you want to just
have one Apache, and let it be the "load balancer" essentially.
Which of course, in our environment, this is not a scalable
solution.
shinta
> -----Original Message-----
> From: [EMAIL PROTECTED] [ mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> ]
> Sent: Monday, March 19, 2001 5:36 AM
> To: '[EMAIL PROTECTED]'; Tim Sullivan;
> [EMAIL PROTECTED]
> Subject: Re[2]: Using Apache/Tomcat in high-traffic site
>
>
> I'm just putting together a prototype on the Internet using Tomcat,
> we've got two Linux boxes and load is spread over the two hosts using
> a BigIP load-balancer. The mod_jk config is ok when you understand
> whats going on, local and remote Tomcat instances aren't specially
> distinguished apart from having a different IP address. mod_jk
handles
> the sticky session part so going in on different web servers each
time
> is fine.
>
> mod_jk could do with better documentation in this regard and its very
> easy to configure it so that it does absolutely nothing and logs no
> errors whatsoever ! Direct all contexts to the load balancer worker
> not the ajp13 workers and have the load balancer worker spread things
> out.
>
> I'm interested in your experience of heap sizes, in my prototype I've
> ignored it, how would I know if I'm near - do you have a feel for how
> much memory you need per session (assuming application doesn't store
> much data in the session).
>
> SteveQ.
>
>
> ______________________________ Reply Separator
> _________________________________
> Subject: RE: Using Apache/Tomcat in high-traffic site
> Author: Tim Sullivan <[EMAIL PROTECTED]> at Internet-po
> Date: 16/03/01 11:24
>
>
>
> Hello Gavin,
>
> I am considering doing the same thing on almost the same
> hardware (e4500 +
> e10000).
>
> Did you end up finding any performance examples or otherwise
> for this? If
> so, could you forward it my way?
>
> Thanks in advance,
>
> -Tim
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [ mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> ]
>
> Sent: Wednesday, March 14, 2001 12:55 PM
> To: [EMAIL PROTECTED]
> Subject: Using Apache/Tomcat in high-traffic site
>
>
>
>
> Hi,
>
> I am looking to use Apache and Tomcat in my company's
> production web site.
> Before I can convince management that this is a good idea I need some
> information so I am confident. If anyone can help I'll be
> very grateful.
>
>
> First of all I'll give you a picture of the overall
> architecture that I want
> to
> create:
>
> 1) For fault-tolerance and scaleability we want to have
> several instances
> of
> Apache running over a number of machines. These will be load
> balanced by a
> pair
> of Cisco Local Director boxes, because we already own a
> couple of them.
> From a
> brief look through the operating manual on Cisco's web site I get the
> impression
> that Local Director cannot support "sticky" load-balancing.
> Please correct
> me
> if I'm wrong.
>
> 2) We will run several instances of Tomcat (version 3.2.1
> most likely) on
> our
> back-end servers. These are a couple of Sun E10000s with 32
> processors
> each.
> These are partitioned up into domains, so that we end up with
> 12 processors
> on
> each machine dedicated to running Tomcat. Each domain has
> 2GB of RAM.
> There
> are other domains dedicated to databases, etc...
>
> 3) Each instance of Apache will be using mod_jk in a
> "sticky" load-balanced
> configuration. Every instance of Apache (and so mod_jk) will
> have workers
> defined for every instance of Tomcat on both E10000s. In
> other words, a
> Tomcat
> instance may receive a request from any instance of Apache.
>
>
> The things I need to know :)
>
> 1) Each request to our site will be assigned seemingly at
> random to one of
> the
> Apache instances by the Cisco boxes. Can the "sticky" part
> of mod_jk cope
> with
> this? i.e. Will mod_jk pass the request to the correct
> Tomcat instance
> even
> though it does not share context information with the other Apache
> instances?
>
> 2) What is the best way of running Tomcat on the large
> E10000s? Should I
> have
> just a few very large processes (say 2 x 800MB max heap) for
> Tomcat or
> should I
> run many smaller processes (say 16 x 100MB max heap)? Has
> anyone got any
> experience with making Tomcat (or any Java based server)
> scale to machines
> of
> this size and power? I want to get good performance, but I
> don't want to
> compromise stability.
>
> 3) Has anyone used Tomcat in a mission critical environment?
> I use it in
> development all the time and I'm very happy with it, but I'd
> like to get
> some
> impression of how it holds up.
>
> 4) Are there any security considerations with this
> configuration? We have
> firewalls, intrusion detection kit, etc... for which we have
> a dedicated
> maintenance team. I'm really only interested in the software
> here. Has
> anyone
> used the new Java 2 security features with Tomcat?
>
>
> Thank you very much indeed!
>
> Cheerio, Woody.
>
>
>
>
>
>
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