If an error occurs while a record is being written, an attempt is made to successfully write the error record. If writing is not successful after several retries and error recovery is not requested, SORT terminates. If error recovery is requested, SORT marks as a bad disk the row of the disk containing the error record. SORT retains the other copy of that row for subsequent use. If possible, SORT continues in full error recovery mode; otherwise, SORT displays “SORT ERROR #31” and continues in error recovery mode for the work file. Further error recovery for the control file is no longer possible. In either case, if SORT is unable to write the error record after the bad row has been marked, SORT terminates. Only one disk row is marked as bad disk on an error so that it is not possible to get into a loop and mark large quantities of disk as bad.