Hi Daniel, target_n_val can be changed at any time and will take effect at the first iteration of the claim algorithm [0] (which usually runs whenever you add/remove nodes from the cluster via the riak-admin command)
On default settings, Riak is able to replicate data to distinct nodes in all clusters with more than 3 nodes. [0] https://github.com/basho/riak_core/blob/develop/src/riak_core_claim.erl#L429 Thanks, Ciprian On Mon, Mar 17, 2014 at 5:50 PM, Daniel Iwan <iwan.dan...@gmail.com> wrote: > Hi Ciprian > > Thanks for reply > I'm assuming 'overlay' you are talking about are vnodes? > When creating cluster and joining 2 nodes to first node (3-node cluster) > there should be possible distributing partitions to guarantee 3 copies are > on distinct machines. Simple sequential vnode assignment would do. > Then I guess it's a matter of calculating distances between indexes within > each of nodes. Partitions that do not meet that criteria should be moved > when scaling up. > > Scaling up in my opinion should be easier as more nodes in the cluster, > sequential partitions are more spread horizontally so probability that a > server will hold sequential partitions decreases. > > With 3 servers it should be guaranteed that at least 2 copies are on > distinct servers. On 5 servers should be guaranteed 3 copies are on > distinct > servers. etc. > > Does Riak give such guarantees? > > Can target_n_val be changed later. What are the implications? Is there a > description what algorithm will be used for partition placement? > > Cheers > Daniel > > > > > > > > > -- > View this message in context: > http://riak-users.197444.n3.nabble.com/Partitions-placement-tp4030664p4030679.html > Sent from the Riak Users mailing list archive at Nabble.com. > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >
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