Continuous Data Protection differs from conventional data protection in two main ways:
- Each change of a primary data stock will also lead to a change in the Backup data stock. This ensures that a copy of the data stock is always available in real-time.
- The data flow changing the data is recorded using the original data stock. Significant places in the data stream can be marked using a Marker.
Because it contains additional information, a greater amount of data is used for the CPD than is contained in the primary data stock. The original data stock plus the data flow up to a specific Marker equals the data stock which corresponds with the Marker at that time.
Markers can be set through application software (e.g. when a database is being reorganised or maintained, or when a data record is being written) or manually by the operator (e.g. when Patches are being installed). These Markers can also be used to navigate in the data stream.
When the available storage space has been filled by the CDP data stock, the original data are merged with the oldest recorded data to create a new basic data stock. The thus emptied storage space is then made available for storing new data records. The oldest data stock which is restored in this manner is the newly generated basic data.