>From "Cassandra the definitive guide" - Basic Maintenance - Repair
Running nodetool repair causes Cassandra to execute a Major Compaction [...] AntiEntropyService implements the Singleton pattern and defines the static Differencer class as well, which is used to compare two trees. If it finds any differences, it launches a repair for the ranges that don't agree. So, although Cassandra takes care of such matters automatically on occasion you can run it yourself as well So now I'm confused ... Cassandra doc says that I have to run it by myself, Cassandra book says I don't have to. Did I misunderstand something? >> I looked around in the code, it seems that AntiEntropy operations are >> not automatically run in the server daemon, but only >> manually invoked through nodetool, am I correct? > >Yes, and it's important that you do run repair: >http://wiki.apache.org/cassandra/Operations#Frequency_of_nodetool_repair
