The Truth About Oracle's Virtualized 12c Database

Oracle announced during Oracle OpenWorld that it had virtualized the database system for multi-tenant operations. That was the chief characteristic cited when Oracle officials were asked what it was about 12c that warranted the "cloud" designation.

But Oracle's use of "virtualized" doesn't necessarily mean what you initially think it does. Oracle 12c is not running under OracleVM or VMware's ESX or any other hypervisor. Instead, the database system itself is behaving more like a hypervisor.

The analogy is imperfect. The database is not emulating the x86 hardware instruction set or passing commands through software directly to the hardware, the way ESX Server and OracleVM hypervisors do.

Instead, Oracle 12c is capable of managing a set of guests or "pluggable databases" beneath its core system. When a database system is virtualized under VMware, it is put, like any other application, inside a virtual machine to be managed by the hypervisor. But Oracle 12c stays independent and instead becomes host for up to 252 pluggable databases. (Most customers will fall short of testing this limit.)

[ Want more on Oracle 12c? See Oracle's Ellison Tries To Outmaneuver SAP Hana. ]

The core database logic isn't cloned and made available to each pluggable database, the way the operating system is inside a VM. Rather, one core system handles all the needs of the pluggable guests. The host and guests reside together in a single "container," a software construct given a set amount of physical resources.

The advantages of this will be immediately evident to IT managers running dozens or hundreds of Oracle systems. Several can be consolidated into one container on one physical server, while maintaining their independent operating characteristics. That would include their own security mechanisms, their own schema and metadata, and their own data dictionary.

Individual identity is maintained because each pluggable database is assigned its own tablespace inside the container. In effect, a defined tablespace represents one application, building a logical barrier around its unique characteristics. As used by Oracle and relational database users in general, tablespace means the storage space where data and indexes are kept until needed by the database system. A tablespace would typically contain multiple tables of data for a given application.

"Each pluggable database has its own private tablespace," noted Andy Mendelsohn, senior VP of database server technologies, in an interview Wednesday at Oracle OpenWorld, a few moments after the cheering had ended for Team Oracle's win of the 34th America's Cup on nearby San Francisco Bay.

Oracle 12c divides up the resources available to the container among the pluggable databases, much as a hypervisor shares physical resources like CPU and RAM among guest applications. The core database logic is time-shared among the pluggable databases, with some perhaps warranting higher priority service than others.

This "virtualized" separation is sure to come up in future Oracle comparisons of it versus the competition. For example, Oracle can now say it has a better way of supplying HR and CRM application services versus Salesforce.com and other vendors. Oracle CEO Larry Ellison has previously said at 2011 and 2012 OpenWorld conferences that virtualization in the cloud is the right direction to go, and separation of one customer's data from another's is a virtue. Salesforce.com was potentially "intermingling" customer data, he claimed. He might have been referring to what he knew was still under wraps inside Oracle's 12c development teams. (Salesforce says its multi-tenant application enforces customer data separation, working in conjunction with the Oracle database.)

A segment of that discussion occurred at OpenWorld with Rex Wang, Oracle VP of product marketing. Asked if the "virtualized" 12c's data protections were better than Salesforce.com's multi-tenant application's, Wang said they were. Asked if he knew of any failures of application-enforced separation of data at Salesforce or elsewhere, such as at banks, insurance companies and other businesses that rely on Oracle, Wang said that if there were, those businesses wouldn't have been eager to publicize them. This debate is likely to be continued.

Among other effects of 12c's form of virtualization, though little noted at OpenWorld, is that database systems become more moveable. A pluggable database on one 12c server can be detached and plugged into another 12c server in a different part of the data center or in a different data center altogether (provided its data feed has been hooked up). This is an echo of VMware's vMotion function for virtual machines.

The 12c containerized database system might quickly build a pluggable database and just as quickly tear it down. Database administrators, noted Mendelsohn, spend a lot of time doing patches and upgrades. They could now be done in a cloned, pluggable database, then swapped in for the older version.

"It's similar to what IT is doing with virtual machines," said Mendelsohn, only Oracle has imported the virtualization concept to the database world and implemented it in a way suitable to more consolidated operations. Mendelsohn said Oracle might see a consolidation phase sweep through the customer base and reduce licenses sold for a short while. At the same time, it will easier to create and maintain database systems. One database administrator can monitor and manage all the databases in a single container using one set of tools.

The result, he expected, would be that the normal growth of data will whet an appetite for more systems and more analytics. Oracle will sell 12c as before, based on the number of CPUs used in running the database. And in the long run, that number is going to continue to go up, he predicted.

Learn more about preparing your apps for the cloud by attending the Interop conference track on Applications and Collaboration in New York from Sept. 30 to Oct. 4.