Various systems, methods, and processes for optimizing access to production data in application development and testing environments are disclosed. If an input/output (I/O) operation is a read operation, a storage location on a virtual storage unit at which the read operation is to be performed is determined. Also determined is whether an earlier write operation was performed at the storage location. If an earlier write operation was performed at the storage location, the read operation is performed on one or more virtual data files. However, if the earlier write operation was not performed at the storage location, the read operation is performed on allocated storage space.