expdp error : ORA-31617: unable to open dump file "/backup/salesdb_backup_02.dmp" for write ORA-19505: failed to identify file "/backup/nightly_backup/salesdb_backup_02.dmp" ORA-27037: unable to obtain file status

expdp parfile=params

content of params.sh:
userid=scott/tiger
parallel=2
.
.
.
ORA-31693: Table data object "HR"."EMP" failed to load/unload and is being skipped due to error:
ORA-31617: unable to open dump file "/backup/salesdb_backup_02.dmp" for write
ORA-19505: failed to identify file "/backup/nightly_backup/salesdb_backup_02.dmp"
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory

Remedy in 11g is use parameter cluster=N

This error occures when parallel parameter is specified in using expdp in RAC databases  and same physical directories does not exists in all nodes. This error is fixed in 11g only using cluster=N