“Infrastructure as a service" (IaaS), deliver computer infrastructure – typically a platform virtualization environment – as a service, along with raw (block) storage and networking. Rather than purchasing servers, software, data-center space or network equipment, clients instead buy those resources as a fully outsourced service. Suppliers typically bill such services on a utility computing basis; the amount of resources consumed (and therefore the cost) will typically reflect the level of activity.
“Database as a service" (DBaaS), deliver database as a service over the Internet, eliminating the need to install and run the application on the customer's own computers and simplifying maintenance and support.
“Platform as a service ” (PaaS), deliver a computing platform and/or solution stack as a service, often consuming cloud infrastructure and sustaining cloud applications. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers
First, cloud architects and database administrators have to choose the right consolidation strategy. Let
us look at some prevailing consolidation strategies.
One can use server virtualization to provision databases packaged as VMs. This model is simple,
provides operating system level isolation, but results in VM
sprawl and other administrative challenges.
The second model offers better consolidation where a number of databases can share the operating
system. These databases can be deployed on single instance or RAC.
One can also think of consolidating further by sharing databases for various applications. This can be
achieved by deploying multiple schemas within the same database.
As we see, all these models have their pros and cons……..
Let us now look at a summarized comparison of the various consolidation models. As we see here, pluggable database combines the best of all the other models and offers excellent consolidation, isolation, manageability and is suitable for any application that is certified to run on database 12c. With the other models, we see certain shortcomings. For example, server virtualization offers good isolation but creates compliance and administrative headaches. Schema based consolidation offers ease of management and patching, but limited isolation. Bottom-line is: while Oracle provides best practice recommendations and blueprints for database as a service, enterprises need to choose among these models based on their individual needs.