Conrado Buhrer wrote:
Hi all,
I'm working on a platform for didactor (same software used on ROC zeeland
website). I'm having a few problems with broadcasting database changes.
Didactor runs on mmbase 1.7.1. We're using tomcat 5.5.
Our setup is quite simple, there are two load balancers running ha.d and
ipvsadm, which round-rob persistent connections to two 'worker' machines.
Database setup is not redundant yet. Once didactor v2 is out it should be.
(If anybody knows of some ready mmbase db redundancy module I'm sure the
didactor people would appreciate it... You can send me some hints on this
too.)
Once a worker machine makes an update to the database a broadcast is made,
and received; I can see it with tcpdump on both worker machines. I believe I
have probably made some configuration error in mmbaseroot.xml perhaps.
Documentation on clustering mmbase nodes seems quite sparse. I would
appreciate some help on setting this up.
All the best, Conrado Buhrer.
Some steps you should do to identify the problem
Step 1
Check with some tools that you can multicast to the other machine.
When this does not work then it is a problem in your network or firewall.
Write down the settings you have to use (host, port and ttl)
The default settings of MMbase are:
host: 224.0.0.1
port: 16080
ttl: 1
The ttl from mmbase is very low and only systems on the same network
segment will receive messages. The ttl setting (multicastttl) was
missing in mmbaseroot.xml as an example, but should work.
Step 2
Turn on debug logging for the following classes
org.mmbase.module.core.MultiCastChangesSender
org.mmbase.module.core.MultiCastChangesReciever
You should see SEND and RECEIVE messages in the log (mmserver messages
are passing regularly). You should get matching receive messages for the
messages send on the other machine.
Step 3
Come back to us, because the multicast itself is working. It is then a
cache flush issue.
Nico
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