Optimizing copy processing between storage processors

Techniques are described for copying data. At a first storage processor, a copy request is received to copy data including copying source data from a source area of a source logical device to a destination area of a destination logical device. The source logical device is owned by the first storage processor and the destination logical device is owned by a second storage processor. The first storage processor receives, from the second storage processor, destination location physical storage mapping information for the destination area. A destination physical device location corresponding to the destination area is determined. The source data from the source area is stored in a first cache location of a first data cache of the first storage processor. The first cache location is modified to indicate it includes write pending data for the destination physical device location. The source data is destaged to the destination physical device location.