The Cassandra Operations page
(http://wiki.apache.org/cassandra/Operations) says:
Unless your application performs no deletes, it is vital that production
clusters run nodetool repair periodically on all nodes in the cluster. The
hard requirement for repair frequency is the value used for
The DistributedDeletes link in that section explains the root reason for
needing to do this. It's not that deletes are forgotten, it's that a write
(deletes are basically tombstone writes) didn't get replicated to all
replicas. For example, at RF=3, write consistency level QUORUM, if one of
the
