Provided are a method, system, and program for managing a relationship between
one target volume and one source volume. For each of the source volume and target
volume, the memory includes: (i) at least one element, wherein each element represents
a range of sequential data units in the volume; (ii) at least one relationship
entry, wherein each relationship entry represents one relationship; (iii) at least
one element pointer associating one element with one relationship entry, wherein
the data units represented by the element are part of the relationship represented
by the relationship entry that the pointer associates with the element; and (iv)
one relationship pointer for each relationship entry associating the relationship
entry with volume metadata, wherein the volume metadata provides information on
the relationship represented by the relationship entry.