US Patent 7953946 Controlled anticipation in creating a shadow copy

Controlling data retention of a collection of data in a data store. An instruction is received to store a shadow collection of data to the data store. The data store has a previous version of the shadow collection of data. An available amount of data storage space on the data store is identified. An amount of data storage space needed is estimated for storing the shadow collection of data to the data store based on the received instruction. It is determined whether the identified available amount of data storage space is sufficient for storing the estimated amount of data storage space. The shadow collection of data is stored to the data store when said determine indicates that the identified available amount of data storage space is sufficient and the previous version is permitted to be deleted or to be overwritten.