> But, I'm thinking about using OldNetworkTopStrat. NetworkTopologyStrategy is where it's at.
A ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 17 Jun 2011, at 01:39, AJ wrote: > Thanks Eric! I've finally got it! I feel like I've just been initiated or > something by discovering this "secret". I kid! > > But, I'm thinking about using OldNetworkTopStrat. Do you, or anyone else, > know if the same rules for token assignment applies to ONTS? > > > On 6/16/2011 7:21 AM, Eric tamme wrote: >> AJ, >> >> sorry I seemed to miss the original email on this thread. As Aaron >> said, when computing tokens for multiple data centers, you should >> compute them independently for each data center - as if it were its >> own Cassandra cluster. >> >> You can have "overlapping" token ranges between multiple data centers, >> but no two nodes can have the same token, so for subsequent data >> centers I just increment the tokens. >> >> For two data centers with two nodes each using RandomPartitioner >> calculate the tokens for the first DC normally, but int he second data >> center, increment the tokens by one. >> >> In DC 1 >> node 1 = 0 >> node 2 = 85070591730234615865843651857942052864 >> >> In DC 2 >> node 1 = 1 >> node 2 = 85070591730234615865843651857942052865 >> >> For RowMutations this will give each data center a local set of nodes >> that it can write to for complete coverage of the entire token space. >> If you are using NetworkTopologyStrategy for replication, it will give >> an offset mirror replication between the two data centers so that your >> replicas will not get pinned to a node in the remote DC. There are >> other ways to select the tokens, but the increment method is the >> simplest to manage and continue to grow with. >> >> Hope that helps. >> >> -Eric >> >
