Space efficient cascading point in time copying

摘要

Embodiments for space-efficient cascading point-in-time copying of source data by creating a plurality of cascading point-in-time target copies, the target copies being created at different points in time, are provided. Data is physically copied form the source to a repository to create a physical copy, and a data mapping is created that associates the physical copy with a most recent target copy.

主权项

1. A computer implemented method for a space efficient cascading point-in-time copying of source data by mapping a plurality of cascading point-in-time target copies, the target copies being created at different points in time, the method comprising:
physically copying data from the source data to a repository to create a physical copy; creating a data mapping that associates the physical copy with a most recent target copy of said plurality of cascading target point-in-time copies, the data mapping indicating shared mapping and non-shared mapping, the shared mapping indicating that an address of the physical copy in the repository is shared with at least one previously created target copy; and updating the data mapping of one or more target copies of said plurality of cascading target point-in-time copies that are older than a designated target copy of said plurality of cascading target point-in-time copies, so as to include information relating to the designated target copy;
wherein the data mapping comprises a leaf of a B-tree structure, and the B-tree structure includes inner nodes and one or more leaves, the inner nodes include information for assisting in searching the B-tree and the one or more leaves indicate the shared mapping and the non-shared mapping.