MANAGEMENT OF EXTENTS FOR SPACE EFFICIENT STORAGE VOLUMES BY REUSING PREVIOUSLY ALLOCATED EXTENTS

A storage controller maintains an allocation space for extent space efficient storage volumes, in response to a request from a host application for storage space, wherein an extent pool is configured to allocate available extents to the host application. In response to a request from the host application to delete data stored in selected extents that are already allocated to the host application, the storage controller deletes the data but continues to maintain the selected extents as being allocated to the host application. In response to a request to write new data, the storage controller writes the new data to the selected extents that are already allocated.