A method for creating a point-in-time copy of a data store. A command to create
a point-in-time copy of an original data store is received. The processing of input/output
operations to the original data store is suspended. A metadata structure of a copy
data store is created. The metadata structure contains a null metadata slab tree,
a backing store register, and a copy record, the copy record containing a pointer
to a metadata structure of the original data store, the metadata structure of the
original data store containing a pointer to the metadata structure of the copy
data store. The processing of input/output operations to the original data store
and to the copy data store is resumed.