Provided are a method, system, and article of manufacture for copying
storage. Copy operations are performed on source storage units to copy to
target storage units, wherein the copy operations create a consistent
copy of the source storage units in the target storage units. While
performing a copy operation to copy from one source storage unit to one
target storage unit, a write operation is restricted from being performed
on the one source storage unit, until the copy operations have been
performed on the source storage units.