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The "Operations" page has been changed by JonathanEllis. The comment on this change is: r/m confusing paragraph about manually changing RS. http://wiki.apache.org/cassandra/Operations?action=diff&rev1=52&rev2=53 -------------------------------------------------- * 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 is not intended to be changed once live, but if you are sufficiently motivated it can be done with some manual effort: + Replication factor is not really intended to be changed in a live cluster either, but increasing it may be done if you (a) read at 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. + The same options apply to changing replication strategy. - 1. anticompact each node's primary Range, yielding sstables containing only that Range data - 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.
