1. A computer-implemented method for uploading a data file over multiple channels from a client computer to at least one remote destination computer in a computing system, the method comprising the steps of: communicating an upload request to the client computer; dividing the data file into a plurality of file components, each file component comprising one or more file slots, wherein each said file component having a restart-capable cumulative hash and a restart-capable hash and each file slot having a restart-capable hash; simultaneously transferring multiple file slots, each file slot being transferred over one of the multiple channels, to upload the data file from client computer to the at least one destination computer; as the data file is transferred to the destination computer, calculating, based on the data file transferred to the destination computer, a destination-side file slot hash based upon the data in each file slot, a destination-side file component hash based upon the data in each file component, and a destination-side cumulative hash based upon the transferred data file; calculating a client-side cumulative hash based upon the data file resident on the client computer; and comparing the destination-side and client-side cumulative hashes to verify integrity of the transferred file, wherein if the client-side and destination-side cumulative hashes fail to match, indicating an error in transmission, then determining in which file slot and in which file component the error has occurred, whereby uploading of the data file is operable to be re-started beginning with the file slot and file component containing the error.