big cache vs. many partitions and replicas placement

Effenberg, Simon seffenberg at
Mon Jan 28 10:47:22 EST 2013


we want to save plenty of mails in riak which are in average 14k big. Our cluster will become between 10 to 20 nodes so the question is: what is better, having more partitions but each has less cache or is it the other way around so having less partitions with more cache size?

Also with an n_val of 3 it is always said, that there is no guarantee for having this on 3 physical nodes but also that it should be distributed evenly. What does it mean? Is there any calculation I can do to get a feeling how often 3 replicas are only on 2 nodes? Or can you say: with 6 nodes and an n_val of 3 it should be the case that almost 99.9 percent is distributed over different physical nodes?


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