Having N replicas more than nodes in the cluster

Germain Maurice germain.maurice at linkfluence.net
Tue May 11 11:07:42 EDT 2010


I'd like to know how works Riak when my bucket has n_val = 3 and only 2 
physical nodes.
Does Riak make 3 copies of the bucket over the 2 nodes or it maintains 
only 2 copies of my bucket on the cluster ?

I'm doing tests of riak and i find some things weird.

I have a two nodes cluster and a bucket with n_val = 3.
I put more than 1 600 000 documents in the bucket and it takes less than 
200 GB with Innostore.
I shut down the second node with "q()." in a "riak console".
Firstly, there was no synchronisation of data on the first node, i 
assume it's better because very similar to a node crash.
Secondly, when i did a read request on a document with :
- ?r=1 -> success
- ?r=2 -> success
- ?r=3 -> fail

An other question, "n replicas" means "1 + n copies" or "n copies" of 
the bucket ?

I really appreciate if you can explain me this behavior ?

Thank you
Best Regards,
Germain Maurice
Administrateur Système/Réseau
Tel : +33.(0)


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