[Building Sakai] More tomcats or bigger tomcats?

[Berg, A.M.]

Hi,

A parallel experience as comparison. For our main LMS we use Blackboard with 5 tomcat servers per T2000 machine. We have 4 T2000 servers making  in total 20 Tomcats for around 30,000 users. The machines have 16 GB of memory. Each JVM has 1 GB for heap. Please remember that you need to add on top pergen space and I think 1 MB per thread to make the total memory used. Some of the 16 GB memory is reserved for Apache/ mod_perl

Alan

Alan Berg

Senior Developer / Quality Assurance
Group Education and Research Services
Central Computer Services
University of Amsterdam



-----Original Message-----
From: sakai-dev-bounces at collab.sakaiproject.org on behalf of John Bush
Sent: Thu 9/17/2009 5:03
To: Joshua Swink
Cc: Sakai-Dev
Subject: Re: [Building Sakai] More tomcats or bigger tomcats?
 
well, I don't have an answer for you, but I'm interested to know as  
well.  We are doing some performance testing right now and this is one  
of things I want to look at.  I think most people on 64 bit platforms  
are running heaps much bigger than 2 GB.  We are going to be looking  
at 1 8GB tomcat vs 2 4 GB tomcats, I don't think our current setup  
lets us look at anything bigger than that.  Hopefully I should have  
some results next week, I'll let you know what we figure out.

John Bush
Development Manager
rSmart




On Sep 16, 2009, at 11:59 AM, Joshua Swink wrote:

> Is it better to run more tomcat instances, sticking with the default 2
> GB heap size, or to run a single tomcat per CPU, using as much memory
> as can be allocated to each one?
>
> We currently run four tomcat instances on two machines, load balanced
> through Apache. Each one has the recommended 2 GB heap size.
>
> Our user load is always on the increase, and I was wondering what is
> the better configuration:
>
> - Increase the heap size on each tomcat's JVM? Perhaps to 3 GB.
> - Leave the heap size at 2 GB and run additional tomcat instances.
>
> Our current servers have 16 GB memory, so that works out to about 4-5
> tomcats per machine if we stay at 2 GB heap per instance. My main
> question is whether people have experienced better performance using
> more 2 GB tomcats, or fewer tomcats with larger heap sizes.
>
> Also, our servers have 2 CPUs each.
>
> Thanks for any advice!
>
> --
> Joshua Swink
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