In Oracle 12c Oracle released a new technology called Multitenant architecture that allowed an Oracle database to function as a container database (CDB) into which one or more pluggable databases (PDB) could be attached. Since its release, Oracle has been continuously enhancing it and adding more features with every release.
Multitenant databases offer a number of benefits like database consolidation, better manageability, database mobility, and easier patching, just to name a few. It was a separately licensed option which is probably the reason why the adoption of this feature was not as widespread.
But this is changing as a result of two changes Oracle has announced.
First, non-CDB architecture was deprecated since 12.1.0.2, and multitenant container database is the only supported architecture in Oracle Database 20c.
Second, Oracle 19c license allows without additional cost, 3 user-created PDBs in a given database at any time.
These changes are making organizations take a closer look at multitenant databases and start planning the migration of their production databases from non-CDB to pluggable databases inside a CDB.
There are multiple ways in which a non-cdb database can be migrated to multitenant architecture. Most methods involve physical copy of data at the storage level or over the network. That's not a problem if the database is small, but what if its size is in tens or hundreds of terabytes! Physically copying large amounts of data takes time. This extended downtime is certainly not desirable, and in many situations may even not be feasible for a mission-critical production Oracle database.
In this article, we'll see how we can leverage the power FlashArray™ snapshots to plugin a non-cdb database (Source) into a container database (Target) without actually moving any data, thereby drastically reducing the time to complete the migration.