primary库：
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /oracle/app/oracle/flash_recovery_area/archivelog
Oldest online log sequence 303
Next log sequence to archive 305
Current log sequence 305
SQL>
standby库：
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination ?/dbs/arch
Oldest online log sequence 0
Next log sequence to archive 0
Current log sequence 0
SQL>
SQL>
------解决思路----------------------
