Patent ID: 7941619

Claim:
A system comprising: a backup storage configured to store a first sequence of two or more backup images of a data source including a first full backup image representing a state of the data source at a first time T 1 and a second full backup image representing the state of the data source at a second time T 2 ; and backup management software stored on a computer accessible storage medium, wherein the backup management software includes instructions that implement a backup converter executable to access the first full backup image and the second full backup image on the backup storage to create a first differential backup image representing the state of the data source at the time T 2 , wherein the backup converter is executable to create the first differential backup image by determining and storing data differences between the second full backup image and the first full backup image; wherein the backup converter is further executable, in response to determining that a storage amount used to store the first sequence of two or more backup images exceeds a designated threshold, to: create the first differential backup image; and store the first differential backup image on the backup storage and to discard the second full backup image from the backup storage such that the second full backup image is no longer accessible anywhere on the backup storage, thereby allowing re-use of storage space made available on the backup storage a result of discarding the second full backup image while still retaining the first full backup image representing the state of the data source at the time T 1 and the first differential image representing the state of the data source at the time T 2 on the backup storage.