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Hi, we are preparing to set up a more or less extensive test suite for deltasync multimaster replication. Since the resolution of conflicts can be arbitrary (as long as it is consistent), I would like to have a way to compare the outcome to a single authoritative DIT, the "observer" below.
Preconditions: - - all servers start with an identical database - - each server has unique serverID assigned
A thought experiment: There are N servers acting as delta-syncrepl providers, arbitrary changes flow to some/all of the servers. The "replication topology" is arbitrary and volatile, but from some moment on it is guaranteed that it will stay strongly connected.
Let us add another server and call it an "observer". An observer acts as a delta-syncrepl consumer to a (possibly changing) set of providers and it never acts as a provider to any of the servers.
Given the above and barring any software bugs, I guess it is intended that if all servers are running recent OpenLDAP the following should hold for the experiment: - - given that the flow of changes stops eventually, the (actual) replication traffic will eventually stop too with all N servers holding the exact same DIT - - given the above, the (actual) replication traffic to the observer too will stop eventually with the observer holding the exact same DIT as the servers.
Are my expectations reasonable or should the experiment be restricted to achieve that outcome of having a reliable observer node? How about generalizing the experiment by allowing that some of the replication connections be plain syncrepl?
Even though this experiment might be exaggerated, I still feel like stating what is a tautology according to the design from my point of view, but I would like to hear whether it is supposed to work even under these conditions.
Cheers, - -- Ondrej Kuznik
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