Vikram, I apologize, I initially just skimmed your question and thought you were asking something entirely different.
While increasing your N value is safe, decreasing it on a bucket with pre-existing data, as you have, is not-recommended and the source of your inconsistent results. Tom On Wed, Jul 27, 2016 at 4:18 PM, Vikram Lalit <vikramla...@gmail.com> wrote: > Thanks Tom... Yes I did read that but I couldn't deduce the outcome if n > is decreased. John talks about data loss, but am actually observing a > different result... perhaps am missing something! > > > On Wed, Jul 27, 2016 at 6:11 PM, Tom Santero <tsant...@gmail.com> wrote: > >> 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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