expdp导出数据时候出现报错如下：
[oracle@jxrac1 exp_dir]$ expdp system/Ora_123654abc directory=cis_dir schemas=jxcmsuer  dumpfile=jxcmsuer.dmp logfile=jxcmsuer.log flashback_scn=21750361864 parallel=4
Export: Release 12.1.0.2.0 - Production on Fri Apr 13 16:17:08 2018
Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options
FLASHBACK automatically enabled to preserve database integrity.
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_03":  system/******** directory=cis_dir schemas=jxcmsuer dumpfile=jxcmsuer.dmp logfile=jxcmsuer.log flashback_scn=21750361864 parallel=4 
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 132 MB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/SEQUENCE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/FUNCTION/FUNCTION
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/FUNCTION/ALTER_FUNCTION
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/STATISTICS/MARKER
Processing object type SCHEMA_EXPORT/JOB
. . exported "JXCMSUER"."JXC_PLAN_REPAYMENT"             48.08 MB  664579 rows
ORA-31693: Table data object "JXCMSUER"."JXC_PLAN_REPAYMENT_180307" failed to load/unload and is being skipped due to error:
ORA-31617: unable to open dump file "/data/back/exp_dir/jxcmsuer.dmp" for write
ORA-19505: failed to identify file "/data/back/exp_dir/jxcmsuer.dmp"
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
ORA-31693: Table data object "JXCMSUER"."JXC_PLAN_REPAYMENT_0301" failed to load/unload and is being skipped due to error:
ORA-31617: unable to open dump file "/data/back/exp_dir/jxcmsuer.dmp" for write
ORA-19505: failed to identify file "/data/back/exp_dir/jxcmsuer.dmp"
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
. . exported "JXCMSUER"."JXC_INVESTMENT_MATCHING"        5.604 MB   34343 rows
. . exported "JXCMSUER"."JXC_U_CREDITORS_RIGHTS_180307"  3.104 MB    3619 rows
. . exported "JXCMSUER"."JXC_HS_AUTO_DEBT_ASSIGNMENT"    1.579 MB   20690 rows
. . exported "JXCMSUER"."JXC_BID_INFO"                   1.198 MB    7414 rows
ORA-31693: Table data object "JXCMSUER"."JXC_U_CREDITORS_RIGHTS" failed to load/unload and is being skipped due to error:
ORA-29913: error in executing ODCIEXTTABLEPOPULATE callout
ORA-31617: unable to open dump file "/data/back/exp_dir/jxcmsuer.dmp" for write
ORA-19505: failed to identify file "/data/back/exp_dir/jxcmsuer.dmp"
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory

修改数据库参数 aq_tm_processes
[oracle@jxrac1 exp_dir]$ sqlplus / as sysdba
SQL*Plus: Release 12.1.0.2.0 Production on Fri Apr 13 16:22:00 2018
Copyright (c) 1982, 2014, Oracle.  All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options
SQL> show parameter aq_tm_processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     2
SQL> alter system set aq_tm_processes=1 scope=memory;
System altered.
SQL> show parameter aq_tm_processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1

重新导出数据，报错消失，导出正常。