[Linux-cluster] A couple of Multicast Questions

[Christine Caulfield]

On 21/06/10 15:07, Dustin Henry Offutt wrote:
> Regarding the CS as released with RH 5.4, 5.5 and as expected with 6.0
> if anything might change...:
>
> Should one adjust the multicast address being used if running multiple
> clusters? If no, how is it that they can differentiate traffic between
> the clusters?

cman sets the multicast addressed based on a hash of the cluster name. 
So if you have two clusters with different names they should use 
different multicast addresses. The hash it uses is fairly primitive 
though, so it's worth checking that the two clusters are using different 
addresses. cman_tool status will tell you this. If you need to change 
the multiast address manually, then do so inside the <cman> tag of 
cluster.conf


> If an unrelated application is on the same network as these clusters,
> should care be taken to change the multicast address being used by the
> cluster(s)?

That's up the the application you are using. If the application uses 
both the same multicast AND port number that openais is using, then you 
will have to change one or the other. It's rather unlikely though.

> Would it be best practice, if altering the multicast address to edit
> /etc/ais/openais.conf or add multicast xtags in the cluster.conf or does
> it not really matter?
\
When using RHCS/cman the openais.conf file is never read. All 
configuration should be in cluster.conf


Chrissie