Infrastructure as a Service (IaaS) is a cloud computing model in which a cloud service provider furnishes the client with the physical computing elements: the network, storage subsystem, physical servers, and the hypervisor running on the servers. This gives subscribers everything they need to create and manage their virtual machines. Therefore, all the cloud infrastructure layers above the hypervisor are the subscriber’s responsibility, as shown in Figure 1-3.
FIGURE 1-3 The shared responsibility model for IaaS
For example, when a subscriber uses Microsoft Azure to create a virtual machine, the provider is furnishing access to a physical server with hypervisor software—presumably Microsoft Hyper-V—running on it. The server has a physical storage subsystem and is connected to a physical network that provides access to the provider’s other servers and the Internet. Using the management tools Azure provides, the subscriber can create a virtual machine containing a specific amount of memory, storage, and number of CPUs—all of which are realized virtually.
Need More Review? Cloud Computing with Microsoft Azure
For more information on cloud computing as realized in Microsoft Azure, see https://azure.microsoft.com/en-ca/overview/what-is-cloud-computing.
The result is a virtual machine that the subscriber can install, configure, and use to run applications like a VM on an on-premises server. The difference is that the subscriber does not have to outfit a datacenter, build a network, procure a physical computer, and install the hypervisor. Instead, the subscriber pays a regular fee for the actual resources that the VM uses. The subscriber can add memory, storage, and CPUs to the VM or remove them as needed, and the subscriber can configure many other settings through a remote management interface. Additional resources incur additional fees, but the process of building a new server takes a matter of minutes instead of days or weeks.
With the IaaS model, the provider is responsible for the physical servers and the physical network, but the subscriber is responsible for managing and maintaining its virtual machines and the virtual network on which they run, as shown earlier in Figure 1-3. Therefore, the provider installs operating system and driver updates on the physical servers, but the subscriber must install any operating system and application updates needed on the virtual machines. The subscriber is responsible for any other VM software, maintenance, and management issues arising.
Note VM Update Management
For an additional fee, Microsoft Azure can provide an Update Management solution that automates the installation of updates and patches on a subscriber’s virtual machines.
Of all the cloud service models, IaaS places the greatest amount of responsibility on the subscriber, and in many instances, this is how administrators want it. By creating and configuring their own virtual machines, administrators can duplicate the environment of their on-premises servers, creating a hybrid cloud-bursting infrastructure that can handle overflow traffic during a busy season.
Organizations with high-traffic websites often run their sites with a dedicated web hosting service provider. However, building the site using virtual machines furnished by a cloud service provider using the IaaS model can often be a far less expensive proposition.
Subscribers can also use IaaS to create a testing and development environment for applications. Rapid deployment and modification of VMs allows administrators to create multiple temporary evaluation and testing platforms and take them down just as easily.
IaaS can also provide subscribers with VMs containing massive amounts of virtual hardware resources impractical to implement in on-premises servers. Large data sets and high-performance computing can require huge amounts of memory and processing power to perform the tasks required for applications such as weather patterning, data mining, and financial modeling. The resources of a high-end cloud service provider make it far less expensive to equip VMs with the necessary virtual hardware than to build physical servers with equivalent resources.