Copy fails with ORA-07455 error and event_log shows the below error.
Error 2015-03-02 15:13:12.358923 2660 1 Compare client: Oracle Error 7455: ORA-07455: estimated execution time (1666 secs), exceeds limit (1000 secs). [sp_declt] [module deq]
Warning messages from the sync log:
It is a Database issue and can be related with lack of free space on UNDO or/and TEMP Tablespaces and also a not well dimensioned value for the database parameter MAX_EST_EXEC_TIME.
Check in the database alert.log for ORA-01555 - Snapshot too Old and/or ORA-01652 Unable to extend temp segments. If found, fix it and run COPY again.
If there is no ORA errors in the alert.log, estimate a good value for MAX_EST_EXEC_TIME. Check Oracle Support Doc Id 277419.1 for more details and run COPY again.
If none of these options work, try to run an export (exp) on the OS level, and check if the issue reoccurs. If it does, contact Oracle Support.