Regardless of whether the client is talking to a load balancer or directly to a server, the behavior is the same: the client is informed of Riak's result after the relevant number of servers have responded. The mechanics of that coordination are hidden from the client.
However, what Riak 1.4.x offers is not strong consistency, no matter how many servers are specified via the R
and W
values. Riak prioritizes availability, so if W=3
and only one server is available, that server will write 3 copies to itself and respond with success. If that server fails as the others come back online, clients will see an older value for that key.
With Riak 2.0, strong consistency will be an option.
For more on the pre-2.0 behavior, see http://littleriakbook.com.