[Spread-users] Question about partitions

Gayathri Dongre g_subrama at yahoo.com
Fri Oct 10 18:26:12 EDT 2003


This is a great product and i'm really enjoying
learning about it!

I'm trying to understand the Spread daemon behaviour
in case of a network partition.

Let's say a network partition occurs between two
daemons in a site. The application at one end tried to
multicast messages M1-M10 to the group after the
partition actually occurred and before the application
received a Membership change message. After the nodes
get connected on the network again, do i expect to see
these messages M1-M10? From my tests using your tools,
it seems like sometimes i do and sometimes i don't.

Which factors or parameters does it depend on? My
guess is that it would depend on the queue size, but
sometimes i don't see any messages.

I have another question that is not necessarily
related to partitions. 

I need to have reliable delivery in my system even in
view of partitions etc. If i choose to send causally
ordered messages, the daemon doesn't really tell me if
my messages, sent just before group membership
changed, were not delivered to ALL the members of the
old membership. Is that right, or am i wrong about
that? Do i have to use SAFE messages to get reliable
delivery in view of partitions, even if i don't need
that level of ordering/stability when the message is

Thanks in advance for your help.

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