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From Apache Wiki <>
Subject [Cassandra Wiki] Update of "Operations" by JonathanEllis
Date Wed, 09 Dec 2009 16:21:59 GMT
Dear Wiki user,

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The "Operations" page has been changed by JonathanEllis.


  Note that with !RackAwareStrategy, succeeding nodes along the ring should alternate data
centers to avoid hot spots.  For instance, if you have nodes A, B, C, and D in increasing
Token order, and instead of alternating you place A and B in DC1, and C and D in DC2, then
nodes C and A will have disproportionately more data on them because they will be the replica
destination for every Token range in the other data center.
   * The corollary to this is, if you want to start with a single DC and add another later,
when you add the second DC you should add as many nodes as you have in the first rather than
adding a node or two at a time gradually.
- Replication strategy may not be changed without wiping your data and starting over.
+ Replication strategy is not intended to be changed once live, but if you are sufficiently
motivated it can be done with some manual effort:
+  1. anticompact each node's primary Range, yielding sstables containing only that Range
+  1. copy those sstables to the nodes responsible for extra replicas under the new strategy
+  1. change the strategy and restart
  == Network topology ==

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