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Principles

We have to build a multi-master replication system. That means the if we have N servers, the total number of connections between all those servers will be equals to : N x ( N - 1 ). If we have 4 servers, we will have 12 possibles connections. If we have 10 servers, we will have 90 possibles relationsetc. For 100 servers, this is 9 000  possibles relations !!! Even if this is a polynomial growth, the reality s totally different. We won't allow such a scheme, which is totally out of control. In real world, having only two servers seems quite common, for small to large organization. If more servers are needed - for scalibility or to build a failover system, then N to N communication network will not be implemented. We will generally select one or two "master" servers which will communicate with a few other servers, like in a chain.

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