Tomcat6 LoadMetrics

[magi]

Hi,

I'm using mod_cluster with two tomcat6 nodes and I'm wondering if loadmetrics are turned on, on tomcat's by default.

The Documentation http://docs.jboss.org/mod_cluster/1.0.0/html/javaproperties.html#d0e1716 says that default loadmetric for Tomcat is

BusyConnectorsLoadMetric.

Mod_cluster sends periodically:

192.168.1.1 "STATUS / HTTP/1.0" 200 76
192.168.1.2 "STATUS / HTTP/1.0" 200 76

I'm wondering if '76' means the LoadFactor for a node.

Thanks in advance

Magdalena

[sudheerk84]

I too have the same doubt , as i have tried with 2 tomcats and all the requests(tried around 4 to 5 requests sequentially) are going to  tomcat1.

When i shutdown tomcat1 requests go to tomcat2.

[pferraro]

Yes - the default load metric is BusyConnectorsLoadMetric.  Yes, 76 is the load factor.  The load factor is a value between 0 and 100.  The greater the number (relative to the other), the more load that node will receive.

[pferraro]

mod_cluster doesn't use round robin balancing, but instead balances based on load.  If you never have simultaneous requests, then there is nothing to balance.  Try sending concurrent requests - then you should see your second node getting utilized.

[magi]

Documentations says:

"The mod_cluster proxy module expects the load factor to be an     integer between 0 and 100, where 0 indicates max load and 100 indicates     zero load"

So, how is it in real?

[pferraro]

Note, I have not contradicted the documentation.  A load factor of 100 indicates that the node is under no load.  A load factor of 0 indicates that the node is under max load.  So, in this extreme scenario, the load balancer will send future requests to the node with the load factor of 100.  In general, the greater the load factor, the more likely the load balancer will direct requests to that node.

[magi]

Thanks for the reply:-)

I  still don't understand mod_cluster_manager, which monitors my nodes - it points the 'Load' is set on:100(on both nodes).

Loadfactor sent by loadbalancer every 5 seconds is set to 76. How to compute it?

Documentations says "Load: (Number) Load factor received via the STATUS messages." - so, value in status messages should be the same as reported via mod_cluster_manager monitor. What causes the difference?

As it stands, I also don't know how to set Smax parameter in Tomcat AS.