Patent ID: 7103737

Claim:
A method in a data processing system, comprising: creating data volumes V 1,1 –V 1,n wherein data volume V 1,1 is created as a point-in-time (PIT) copy of a volume V, wherein each data volume V 1,x of data volumes V 1,2 –V 1,n is created as a PIT copy of data volume V 1,x−1 , and wherein each of data volumes V 1,1 –V 1,n and V 2,1 –V 2,m are initially created as virtual PIT copies; creating data volumes V 2,1 –V 2,m wherein data volume V 2,1 is created as a PIT copy of the volume V, and wherein each data volume V 2,y of data volumes V 2,2 –V 2,m is created as a PIT copy of data volume V 2,y−1 generating a refresh instruction for refreshing the data contents of data volume V 2,y to the data contents of one of the data volumes V 1,1 –V 1,n ; converting data volume V 2,y from a virtual data volume into a real data volume after generation of the refresh instruction; modifying first data of data volume V 2,y before the conversion of data volume V 2,y .