Restore database from NFS storage

In this blog the restore of an Oracle database is described. The database was, before it got lost, daily backed up to an NFS mounted storage device. Next to that, every 10 minutes backups of the archived log files were created.

Starting point:

• Clean installed VM, no database running
• File systems created and sized to needed size
• No DB, no spfiles etc. found on the system

 

Steps:

• Set ORACLE_SID
• Mount NetApp storage for this database under /mnt/backup/$ORACLE_SID
• Find newest backup file that contains the spfile and restore it

     ls -lrt /mnt/backup/$ORACLE_SID/c*

     If you do not have a valid spfile or init.ora RMAN has the ability to nomount an instance without the requirement of a spfile. This will allow you to restore your spfile from a valid backup.

$ rman target / 
( do not connect to the recovery catalog, as it will not find this forcefully started instance)

RMAN> startup nomount force;

     To be able to restore the spfile, we do need the DBID for the database to be restored. Use SQLplus and query the DBID from the RMAN catalog;

SQL>  select db_id from  db where reg_db_unique_name='DBAPRDC';

• Return to RMAN and execute the following statements:

RMAN> set DBID=<ID from query>;

RMAN> restore spfile from ‘<file found in ls -lrt command>';

-          Shutdown the database and restart  it in nomount using the restored spfile and then connect to the RMAN catalog:

RMAN> shutdown immediate;

RMAN> startup nomount;

Quit RMAN and restart using the recovery catalog;

rman target / rcvcat /@tsmora

• Restore the controlfiles from the same backup file that held the spfile:

RMAN> restore controlfile from ‘<file found in ls -lrt command>’;

The control files are automatically restored to the correct location.

• Restore and recover database

Now it is time to restore and recover the database.
Since we assume that we don’t have anything but the backup of the database, a full recovery is not possible as we are missing the latest redo information from the online redo files. We do have to recovery with the amount of redo we have from archived log backups:

RMAN> alter database mount;

RMAN> restore database;

RMAN> recover database until available redo;

Depending on the database size, this may take a while.

• Open the database using RESETLOGS, to let the new redo-log file being created:

RMAN> alter database open resetlogs;

That completes the restore of the database.
Remember that the last couple minutes between the latest archivelog backup and the point in time where database got lost are gone. Data inconsistencies may therefore exist.