A completion state of FAILURE indicates that the operation encountered an error condition or terminated before completion. A completion state of SUCCESS indicates that the operation ran to completion, but in some situations may have encountered and reported conditions that would affect the outcome of the operation. The total bytes that is reported is the number of bytes of source data that was processed in the transaction. It does not include any meta data that might be in the output.
None.
If the completion state is FAILURE, then review the activity log and the event log to try to determine the cause of the failure. If the completion state is SUCCESS, the activity log and the event log can still be checked for warning messages regarding conditions that could have affected the operation.