Database Reference
In-Depth Information
When you use RMAN to back up your multitenant database, you use the RMAN
BACKUP
DATABASE
command just as you would when backing up a non-multitenant database. You will
also use the same backup database options (such as
PLUS ARCHIVELOG DELETE INPUT
) as you
always have.
In contrast, if you issue a
BACKUP TABLESPACE
or
BACKUP DATAFILE
command while
connected to the CDB, then the tablespaces or data files of the root CDB are backed up.
Tablespaces and data files of all of the PDBs are not backed up. You need to connect
directly to the PDB in order to back up specific PDB tablespaces and data files. We will
discuss this in the next section.
Here is an example of a full backup of a CDB:
C:>set ORACLE_SID=mycdb
rman target=/
backup database plus archivelog delete input;
Nothing looks all that different, does it? First, we set the
ORACLE_SID
to the name of the
CDB, which is called
mycdb
. This is the same thing we do with regular Oracle databases.
The result of this backup is that the CDB is backed up and all of the underlying PDBs are
also backed up.
Note that in this backup we assumed that the CDB was in ARCHIVELOG mode.
If the CDB was in NOARCHIVELOG mode, then we would need to shut down and mount
the CDB before starting the backup. We would then need to reopen the CDB and all of the
PDBs after the backup was complete.
We simply had RMAN log into the CDB itself. By doing so, when we execute a backup it
backs up the entire database. That includes the CDB and all of the PDBs. You can use pretty
much all of the RMAN backup features when backing up a CDB. These include things like
compressed backups, incremental backups, multisection backups, adding tags, and so on.
Backing Up PDBs with RMAN
Now that we have discussed backing up the CDB with RMAN, the next step is backing up
the PDBs. Backing up the individual PDBs is similar to backing up the CDB. In this section,
we will discuss backing up the root container, which is part of the overall CDB. We will
then discuss backing up individual PDBs in the database with RMAN.
Keep in mind that the normal way to back up the PDBs in the database is to
back up everything at the CDB level. Backing up a PDB should not be con-
sidered a normal way of backing up an entire CDB.
Recall that a PDB (or a container) is the equivalent of a database. It makes sense, then,
that you will need to have a way to back up your PDBs. Typically, your backup process will
back up the CDB and all of the subordinate PDBs at the same time.
There may be cases where you will wish to back up specific PDBs. For example, you
might have just created or plugged in a PDB and you want to quickly back it up. Or per-
haps you have a very active PDB that you want to back up more frequently.
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