> On Apr 3, 2015, at 10:38 AM, Shankar Dhanasekaran <shan...@opendrops.com> > wrote: > > hi, > For the organization that I am working for, it seems like 25tb of storage is > needed. Reading riak docs, it's mentioned that at least 5 servers should be > put in place. > > what is the harm in having only 2 riak nodes? will this reduce performance? > or cause loss of data? Since Riak is masterless, either one of the server > will have the data at any point of time.
If you have only two nodes and you incur one failure, you will no longer be able to write to a majority quorum [1], which means that a subsequent failure will result in potential unrecoverable data loss. This is why the official recommendation used to be 3 nodes. We’ve changed that to 5 nodes because this is the minimum amount of nodes needed to ensure all copies of each object are stored on different physical nodes. [2] - Chris [1] This assumes a default configuration with n_val = 3. [2] The partition / cluster claim algorithm attempts to ensure that all preference lists are on a disjoint set of nodes. Christopher Meiklejohn Senior Software Engineer Basho Technologies, Inc. cmeiklej...@basho.com _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
