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An Oracle blog about Exadata

  • June 16, 2018

Snapshots in the Exadata Cloud

Brian Spendolini
Database Cloud Services Product Manager

Building on the previous blog entry by Gurmeet (Exadata Snapshots: Simple, Secure, Space Efficient), we are going to see how we can create snapshots in the Exadata Cloud. 

Snapshot PDBs

With the Exadata Cloud (Cloud Service and Cloud at Customer) we have two ways to create snapshots on our services. The first method is via SQL plus and works exactly like what was shown in the previous blog post. You need to have created a SPARSE disk group when you initially provisioned the service.

Once we log into our Exadata Cloud and choose a database to work with, we can choose a PDB we want to create a clone from. We can see what PDBs are available with the following SQL:

SQL> show pdbs;

 

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED

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

     2 PDB$SEED                           READ ONLY  NO

     3 EIGHTPDB                           READ WRITE NO

We see we have the EIGHTPDB to work with. We first need to shut the PDB down on all nodes:

SQL> alter pluggable database EIGHTPDB close instances=all;

 

Pluggable database altered.

Then we put it into READY ONLY mode:

SQL> alter pluggable database EIGHTPDB open read only instances=all;          

 

Pluggable database altered.

And now we create our PDB Snapshot copy using the SPARSE disk group:

SQL> create pluggable database CLONEPDB from EIGHTPDB tempfile reuse create_file_dest='+SPRC4' snapshot copy keystore identified by "PASSWORD";

Pluggable database created.

Being a cloud database, TDE is on by default thus we need the keystore identified by "PASSWORD";  clause with the PASSWORD being the one you supplied upon database creation. Finally, open the snapshot PDB:

SQL> alter pluggable database CLONEPDB open read write instances=all;          

 

Pluggable database altered.

 
Thats it, we have a PDB snapshot copy that uses the SPARSE disk group for changes.

 

Snapshot Masters

The second method is taking a shapshot master in the UI or via a REST service. Once we have that snapshot master, we can create sparse clones using the SPARSE disk group. Here is how you do just that. In the UI, view the database details. On the left side of the page in the Administration tab. Click that tab.

Now you click the Snapshot subtab.

Here we can see the Snapshot Master details. You can click the Create Snapshot Master button to bring up the create modal.

In this modal we can create our snapshot master by giving it a name, a database name and password. We can use the node subsetting feature by clicking the Hostnames field and selecting what nodes of the service we want this snapshot to run on. 

On the bottom of this modal is an ACFS checkbox. Using this checkbox we place this clone's oracle binaries on an ACFS mount saving space. Now this isn't for a production environment but would work well for test and development. Lastly we can choose to also clone the source oracle home rather than create a new one. 

Once you fill in this modal, we can click create to start the snapshot create process.

Once the snapshot is created, we can see it in the UI.

Use the popup menu on the left to create a clone from this snapshot master. This clone uses the SPARSE disk group for any changes to the read only snapshot master.

Once the clone it created, you can use it just as you would any database on the Exadata Cloud Service.

To see a video of this in action, click here.

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