It is broadly known that in an operating system, if any file is deleted, Discard will be issued to underlying storage device. When user deletes file through Operating system, it is not physically deleted from the storage medium, as a matter of fact, this file data is marked as Invalid but remains in the unmapped address space. In another instance, when host performs over write on the previously written logical space and then this previously written memory space can be invalidated by discard operation.