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The "Operations" page has been changed by JonathanEllis. The comment on this change is: explain modifying RF. http://wiki.apache.org/cassandra/Operations?action=diff&rev1=11&rev2=12 -------------------------------------------------- 1. copy those sstables to the nodes responsible for extra replicas under the new strategy 1. change the strategy and restart + Replication factor is not really intended to be changed in a live cluster either, but increasing it may be done if you (a) use ConsistencyLevel.QUORUM or ALL (depending on your existing replication factor) to make sure that a replica that actually has the data is consulted, (b) are willing to accept downtime while anti-entropy repair runs (see below), or (c) are willing to live with some clients potentially being told no data exists if they read from the new replica location(s) until repair is done. + + Reducing replication factor is easily done and only requires running cleanup afterwards to remove extra replicas. + == Network topology == Besides datacenters, you can also tell Cassandra which nodes are in the same rack within a datacenter. Cassandra will use this to route both reads and data movement for Range changes to the nearest replicas. This is configured by a user-pluggable !EndpointSnitch class in the configuration file.
