Pluggable DB Snapshot

Cloning a database.Very simple to say, massive business value and can be on of the hardest things to do. Let’s quickly review some of the ways to clone a database.

Method	Pros	Cons
RMAN	Not Complex Error Free Somewhat Fast Cross Storage Only DBA Skills	Initial Setup Can Be Painful Slow backup devices
DataPump	Cross Platform Partial Clones Cross Storage Only DBA Skills	Slow Error Prone
SAN Clone	Fast Simple	DBA and SAN Skills Extra SAN License Storage Vendor Lock In

With Oracle Database 12c there is a new method that combines most of the strengths of SAN cloning with only needing a DBA. If you have a PDB that you need to clone and the clone PDB will be in the same CDB you can use a new snapshot clone feature. There a few requirements

The cloned PDB and source PDB must be in the same CDB

The storage must be ACFS, ZFS Storage Appliance or NetApp

The source PDB can’t be deleted as long as the cloned PDB is present

The source PDB must be in read only mode

For this example we are going to use ACFS. First we confirm there are zero ACFS snapshots.

# acfsutil snap info /u01/acfsmounts/data_vol1/
    number of snapshots:  0
    snapshot space usage: 0

Then we can run the create pluggable database command using the snapshot copy command. The path_prefix specifies where the new PDB data files will be stored.

SQL> create pluggable database oltpdev2 from oltpdev1 snapshot copy path_prefix = '/u01/acfsmounts/data_vol1/MYCON/';

Pluggable database created.

Next we can confirm a snapshot has been created. Then we can open the new cloned PDB.

# acfsutil snap info /u01/acfsmounts/data_vol1/
snapshot name:               E2741E022F0469AAE0432902A8C0C382
RO snapshot or RW snapshot:  RW
parent name:                 /u01/acfsmounts/data_vol1/
snapshot creation time:      Fri Jul 26 20:12:51 2013

    number of snapshots:  1
    snapshot space usage: 135536640

SQL> alter pluggable database oltpdev2 open;

Pluggable database altered.

In less than 60 seconds we have a clone of our PDB ready. After we are done with the clone we can drop the PDB and see the ACFS snap go as well.

SQL> drop pluggable database oltpdev2 including datafiles;

Pluggable database dropped.

# acfsutil snap info /u01/acfsmounts/data_vol1/
    number of snapshots:  0 (active)
                          1 (delete pending)
    snapshot space usage: 155922432

The PDB has been deleted and ACFS is in the process of cleaning up the snap.

• 12c
• ACFS
• cloning
• database
• oracle
• pdb
• pdb data files
• snapshot copy
• storage vendor