The mechanics behind "virtualization" is called "provisioning." There are basically two kinds of provisioning in the context of Oracle databases.

• CPU provisioning
• Data provisioning

CPU Provisioning

Using the Oracle Grid database, CPUs can be added and subtracted as needed, even when an application is running! Why would you want to do that? Suppose you were a Fortune 100 company that had to run regular monthly financial general ledger reports. Toward the time when general ledger reports needed to be generated, more CPUs could be added to handle the increased computational load during that time. When load (regular monthly transaction processing) was low again, those CPU "cycles" could be used in some other area of the business.

Data Provisioning

Provisioning data allows transportable databases, even portions of a database or individual tables. Tables can be detached from one database and re-attached to another database. Looking again at the financial DB example, some data might be needed to enhance the monthly general ledger report. The data could be connected to the general ledger function until the reports are completed, then it could go back to original database for normal updating, editing, etc.

Oracle handles this by manipulating database "meta" data, instead of shutting down DB, moving table and then restarting application. The moving of data and tables is done logical, instead of physically moving the files physically to a new location on the disks.

A companion product, called Oracle Streams, allows the detached data to be updated according to user's criteria and rules. This makes the data, in effect, location independent.

The Oracle database engine on top of Linux figures out how to "provision" CPUs and data seamlessly within the application, even while the database is running and being accessed.

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