a backup copy of a source data volume is created by first performing an instant virtual copy with source volume identifier suspended , then creating a physical tape backup copy from the instant virtual copy with the source volume id being reintroduced . this creates an exact duplicate of the source volume with minimal impact on access to the source volume . moreover , the resultant backup copy is less costly and error prone because it is created by a machine - automated process rather than various commands issued by a system administrator . in addition , by differentiating the volume ids during intermediate copy steps , the invention is more fault tolerant since failure of the storage subsystem will not result in source and a temporary copy having confusingly indistinguishable volume ids .