Vikram, John Daily wrote a fantastic blog series that places your question in context and then answers it.
http://basho.com/posts/technical/understanding-riaks-configurable-behaviors-part-1/ Tom On Wed, Jul 27, 2016 at 4:07 PM, Vikram Lalit <vikramla...@gmail.com> wrote: > Hi - I have a Riak node with n_val=3, r=2, w=2 and have just one > key-object stored there-in. I'm trying to test various configurations to > better understand the system and have the following observations - some > dont seem to align with my understanding so far, so appreciate if someone > can throw some light please... Thanks! > > 1. n=3, r=2, w=2: Base state, 1 key-value pair. > > 2. Change to n=2, r=2, w=2: When I query from my client, I randomly see 1 > or 2 values being fetched. In fact, the number of keys fetched is 1 or 2, > randomly changing each time the client queries the db. Ideally, I would > have expected that if we reduce the n_val, there would be data loss from > one of the vnodes. And that for this scenario, I would still expect only 1 > (remaining) key-value pair to be read from the remaining two vnodes that > has the data. Note that I dont intend to make such a change in production > as cognizant of the recommendation to never decrease the value of n, but > have done so only to test out the details. > > 3. Then change to n=2, r=1, w=1: I get the same alternating result as > above, i.e. 1 or 2 values being fetched. > > 4. Then change to n=1, r=1, w=1: I get 3 key-value pairs, all identical, > from the database. Again, are these all siblings? > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > >
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