Recovering when system data file is lost

Recovering when system data file is lost:

Previously we have taken the HOT backup to /u01/oracle/app/oradata/pavan/database_1/HOT_BKP/ path. Now whenever a system datafile got missed, deleted, corrupted, overridden or disk errors occurred then database will be shutdown.

In this case we need to recover the system datafile by restoring the file from /u01/oracle/app/oradata/pavan/database_1/HOT_BKP/ to /u01/oracle/app/oradata/pavan/database_1/.

1. Before proceeding with recovery operation we need to shut down the database (generally it will shut down automatically).

SQL> SHUT ABORT

2. Now copy the files from backup location to datafiles location. This is restoration of system datafile.

cp   /u01/oracle/app/oradata/pavan/database_1/HOT_BKP/system01.dbf /u01/oracle/app/oradata/pavan/database_1/

3. Start the database in mount state

SQL>STARTUP MOUNT

4. Now we shall be doing recovery operation

SQL>RECOVER  DATAFILE 1;

In this process it will start applying all available archivelogs to the database and recovers it. We need to cancel once all archive logs are applied.

Enter cancel for cancelling the operation. Or else we can give AUTO to apply all archive logs  

5. Bringup the database in open mode .

SQL>ALTER DATABASE OPEN;

SQL> SELECT STATUS FROM V$INSTANCE;

STATUS

------------

OPEN