US Patent 7231544 Restoring data from point-in-time representations of the data

A system includes a controller to store point-in-time representations (or snapshots) of data taken at different time points from storage unit of a storage subsystem. Data can be restored from one of the point-in-time representations, with point-in-time representations taken later than the one point-in-time representation maintained enabled to allow a subsequent restoring of data from the later point-in-time representations.