Distributed Relational DatabasesReplicationShared Nothing and Shared DiskNonrelational Distributed DatabasesMongoDB Sharding and ReplicationShardingSharding MechanismsCluster BalancingReplicationWrite Concern and Read PreferenceHBaseTables, Regions, and RegionServersCaching and Data LocalityRowkey OrderingRegionServer Splits, Balancing, and FailureRegion ReplicasCassandraGossipConsistent HashingReplicasSnitchesSummary