Time for action – recovering a primary database using a standby database disk backup

1. Let's simulate a case where a datafile is lost by renaming one of the datafiles. Shut down the database, rename the datafile with the mv command, and start the database again. We'll see the cannot identify/lock data file error on startup.

   SQL> shutdown immediate
   
   $ mv /u01/app/oracle2/datafile/ORCL/users01.dbf /u01/app/oracle2/datafile/ORCL/users01.dbf.old
   
   SQL> startup
   ORACLE instance started.
   
   Total System Global Area 1603411968 bytes
   Fixed Size                  2213776 bytes
   Variable Size             872417392 bytes
   Database Buffers          671088640 bytes
   Redo Buffers               57692160 bytes
   Database mounted.
   ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
   ORA-01110: data file 4: '/u01/app/oracle2/datafile/ORCL/users01.dbf'
   

2. Now we'll run an RMAN datafile backup using the standby database as the source and locating the backup file in the primary database. Connect the standby...