Fault domains are defined which reflect, either physically or virtually, the topology of a networked computing environment. These defined fault domains are then used to control where cached data is replicated when running in a write back cache mode. Unlike known replication approaches, the present approach replicates such data according to a user's defined data policy and based on the defined fault domains thereby avoiding the user having to keep track of changes in computing system configurations or update their data policy when virtual machines migrate from one host computing system to another.