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The "VirtualNodes/Balance" page has been changed by EricEvans: http://wiki.apache.org/cassandra/VirtualNodes/Balance?action=diff&rev1=2&rev2=3 Comment: balance vs. intentional imbalance When migrating a legacy cluster with one-token-per-node to virtual nodes, the existing range is carved up into `num_tokens` new ranges. These new ranges are still contiguous however, and a means of randomizing their placement is needed. + <<Anchor(implementation)>> == Implementation (Draft) == + === Considerations === + In the most basic sense, ''balanced'' means that each node has 1/n of the token-space, so adjusting ownership for [[#heterogeneous_nodes|heterogeneous nodes]] is implicitly about ''unbalancing''. This is important because, if for example, you reduced ownership of a node to say (1/n)*.8, you expect that imbalance to persist, and not be balanced-away by operations on other nodes. + + ''Note: This will likely require storing state, in the form of an offset, on each node.'' + === Nodes / Cluster === The most straightforward method of effecting ownership is a token move (i.e. relocating a range from one node to another). Exposing this with JMX would allow implementing all of the required operations client-side.
