Hiii, I have created Oracle 10g Primary database where control file locations are as follows: *control_files='P:oracleproduct10.1.0oradatatcengcontrol01.ctl','C:oradatatcengcontrol02.ct l','E:oradatatcengcontrol03.ctl' Then I have created standby database in standby server where the control file locations are as follows: *control_files='C:oracleproduct10.1.0oradatatcengcontrol01.ctl','D:oradatatcengcontrol02.ct l','D:oradatatcengcontrol03.ctl' Now if I give command 'alter system switch logfile;' no. of times in Primary server then check it in Standby by 'SELECT SEQUENCE#, FIRST_TIME, NEXT_TIME FROM V$ARCHIVED_LOG ORDER BY SEQUENCE', its showing the increasing SEQUENCE# properly. But if I want to open the standby database by the command 'alter database open read only;' then its showing error as SQL> alter database open read only; alter database open read only * ERROR at line 1: ORA-16004: backup database requires recovery ORA-01157: cannot identify/lock data file 1 - see DBWR trace file ORA-01110: data file 1: 'P:ORACLEPRODUCT10.1.0ORADATATCENGSYSTEM01.DBF' Can anyone please tell me where I have made the mistake? Regards, nil

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