Configuring the security keyspaces replication factors

Increase replication factors (RF) for security keyspaces which manage authentication and authorization to prevent lockouts and ensure consistency across the cluster.

Configure the replication factors appropriate for using DSE Security in production environments. Change the replication class to NetworkTopologyStrategy the replication factor of 3-5 for the following security keyspaces:
  • system_auth
  • dse_security
Note: DSE stores authentication and authorization in the security keyspaces. When system_keyspaces_filtering is disabled, all authenticated users have full read access to security_auth and dse_security keyspaces.

Default replication factors

The default replication factor for the system_auth and dse_security keyspaces is 1.

Each of these must be updated in production environments to avoid data loss. DataStax recommends changing the replication factor before enabling authentication. DSE uses a consistency level of LOCAL_ONE for all security keyspaces queries, except when using the cassandra role. For the cassandra role, DSE uses the consistency level QUORUM. Only use the cassandra role to login and create your own full access account and then drop the cassandra role.

Warning: Increase the RF before enabling DSE authentication. Default login account, cassandra, executes all requests with QUORUM and may fail with an RF of 1.

Recommended replication factors

Determine the appropriate RF based on your failure tolerance and the size of your deployment.

  • system_auth: Required for each log in and for every action that affects a database object. Once a user logs in their credentials, roles, and permissions are cached for a period set in the cassandra.yaml, see Security properties. Contains LDAP, native authentication, and authorization related data. When the keyspace is unavailable logins and actions may fail. When located on a node in another datacenter, may cause delays that also can lead to failures. The keyspace tables are relatively small.

    DataStax recommends using a replication factor of 3, 4, or 5 per datacenter.

    Note: DSE caches security data, to adjust cache interval see Security properties.
  • dse_security: Required for each log in and for related DSE services. Contains DSE Analytic (Spark), DSE Client digest tokens, and other Kerberos related data. Less critical for pure database activities.

    DataStax recommends using a replication factor of 3, 4, or 5 per datacenter.

CAUTION: Never set the replication factor greater than the number of nodes in the datacenter.

Procedure

To change the replication factors (RF) of the security keyspaces:

  1. Change the system_auth keyspace RF:
    ALTER KEYSPACE system_auth
        WITH REPLICATION= {'class' : 'NetworkTopologyStrategy', 
                           'data_center_name' : N, 
                           'data_center_name' : N};
    Note: Every time you add or remove a datacenter, you must manually reconfigure the system_auth keyspace.
  2. Change the dse_security keyspace RF:
    ALTER KEYSPACE dse_security
        WITH REPLICATION= {'class' : 'NetworkTopologyStrategy', 
                           'data_center_name' : N, 
                           'data_center_name' : N};
    Important: Every time you add or remove a datacenter, you must manually reconfigure the dse_security keyspace. If DataStax Enterprise or Spark security options are enabled on the cluster, you must also increase the replication factor for the dse_leases keyspace across all logical datacenters.
  3. Run the nodetool repair on the security keyspaces.
    nodetool repair --full system_auth
    nodetool repair --full dse_security
    Note: After changing the replication strategy, you must run nodetool repair with the --full option.