Increasing the replication factor increases the total number of copies of keyspace
data stored in a Cassandra cluster.
Increasing the replication factor increases the total number of copies of keyspace
data stored in a Cassandra cluster. It is particularly important to increase the
replication factor of the system_auth keyspace if you are using security features
because if you use the default, 1, and the node with the lone replica goes down, you
will not be able to log into the cluster because the system_auth keyspace was not
replicated.
Procedure
-
Update a keyspace in the cluster and change its replication strategy
options.
ALTER KEYSPACE system_auth WITH REPLICATION =
{'class' : 'NetworkTopologyStrategy', 'dc1' : 3, 'dc2' : 2};
Or, change the replication strategy from NetworkTopologyStrategy to
SimpleStrategy:
ALTER KEYSPACE eval_keyspace WITH REPLICATION =
{ 'class' : 'SimpleStrategy', 'replication_factor' : 3 };
-
On each affected node, run nodetool repair.
-
Wait until repair completes on a node, then move to the next node.