1. A method for managing data, comprising: receiving a data request to a target track in a relationship, wherein the relationship associates a source track with the target track; submitting a destage request to destage the source track in response to the data request to the target track, wherein executing the data request to the target track is conditioned on receiving a completion response to the destage request; if the source track is not in cache, returning a complete response to the destage request; if the source track was in cache when the relationship was established, adding the destage request to an Input/Output (I/O) queue for the source track; and after the source track is destaged in response to processing the destage request in the I/O queue, returning the complete response to the destage request.