Do you know the fact that when you kill the data pump job in Oracle 10g (using KILL_JOB), it leaves the dump file created thus far . In order to re-execute the job, either you have to delete the dump file or use the set REUSE_DUMPFILES=Y. Some time you also need to change the JOB_NAME as master table is left behind OR table needs to be dropped.
But in 11g, it is improved so killing Data pump jobs cleans up – partially created dump files, Master table. It is very useful as we don’t have to perform manual steps in order to re-execute same data pump.
Oracle Enablement 