rac下 expdp 报错：ORA-31693 ORA-31617 ORA-19505 ORA-27037

rac expdp导出时报错：
ORA-31693: Table data object "scott"."dept" failed to load/unload and is being skipped due to error:
ORA-31617: unable to open dump file "/home/oraclerac/dump_dir/oravs_expdp_05.dmp" for write
ORA-19505: failed to identify file "/home/oraclerac/dump_dir/oravs_expdp_05.dmp"
ORA-27037: unable to obtain file status
错误原因：
在RAC环境下如果PARALLEL参数设置大于1，进程会在RAC的各个节点上进行导出。如果导出目录不共享的话就会报错
解决方法：
1、设置为共享的directory；
2、导出语句添加cluster=n选项，指定只在本地导出