Policy-based performance of continuous data protection on protected data. A write request targeted to a portion of the protected data is detected. In addition, a journaling policy data structure(s) is accessed. The journaling policy data structure represents policy for how frequently to journal write request to a backup medium and/or what backup medium to journal write requests to depending on one or more characteristics of write request targets. The journaling policy data structure is then used to determine whether the write request should be presently journaled and/or to identify the backup medium that the write request should be journaled to based on the one or more characteristics of the portion of the protected data targeted by the write request. The journaling policy may, but need not, be selected so as to preserve storage and/or network bandwidth associated with the journaling process.