Mailing List Archive

VIP acquisition in case of Network partition and remerge

We tested wackamole using 3 nodes A,B and C

A single virtual IP is configured

Initially A acquired the VIP. We unplugged A from LAN(by pulling out the
Network cable). Now B has acquired the VIP.When we tried to reach the
VIP through putty via ssh. It got connected to B.

Then we connected A back to the LAN.When A is connected back to the LAN,
for some amount of time "wackatrl -l" in A shows that A is the master.
"wackatrl -l" in B and C shows that B is the master.

In this scenario we got the following two different behaviours.

1. A comes to know that B has acquired the Virtual IP after sometime.
A,B and C shows that B is the master.

2. A acquires the VIP after sometime. "wackatrl -l" in A,B and C shows
that A is the master.

Can anyone throw some light on why there are 2 different behaviours for
the same scenario. For some amount of time the virtual IP is covered by
both A and B. On what basis the IP conflict will be resolved.

Also can someone explain in which order the state message will be
sent/received when a view change message is sent by group communication
system. Will the state messages be sent/handled independent of the other
members in group or is there any dependency (i.e the state message will
be sent by the second member in the process list maintained by group
communication system after handling the state message from the first


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