What is IaaS (Infrastructure-as-a-Service)

Cloud computing is one of the basic building blocks of modern companies, as renting and using virtualised resources in the cloud not only provides a high degree of flexibility, but also saves in-house IT departments a lot of effort. If you opt for services such as software as a service (SaaS), platform as a service (PaaS), or infrastructure as a service (IaaS), you benefit not only from practical scaling and billing models, but also skip unpleasant tasks like installing and maintaining the individual software and hardware components, since this becomes the provider’s responsibility. The advantages of cloud computing are quickly obvious with the IaaS model especially, where you rent a complete IT infrastructure.

Infrastructure as a service, or IaaS for short, is a service where a provider rents out its own IT infrastructure and makes it available to use online. To do this, the cloud provider usually operates its own data centres where the corresponding hardware is stored, administered, and maintained. By doing this, IaaS providers can offer access to computing power (processor, memory, hard drive space) and complete network structures (including firewalls, routers, and security/back-up systems), the scope of which you, as a customer, can freely dispose of. You can choose which infrastructure you want to use, how many servers, routers, firewalls you want to use, and what performance data (CPU, RAM, etc.) the various network elements should have.

The rented IaaS resources can be scaled up or down at any time if you want to integrate an additional server or reduce the computing power. With most providers, however, you only pay for the components that you actually use. This high flexibility results from the fact that infrastructure as a service offers are generally not bound to dedicated hardware, which allows the provider to distribute its data centre resources among its customers as optimally as possible. To ensure reliability and security of its service in the long run, the provider also takes care of the maintenance and modernisation of data centre hardware and the installation of relevant security systems and devices. Of course, this also includes replacing defective parts.

Infrastructure as a service works according to the shared responsibility principle. Providers as well as customers need to take on different areas of responsibility in order to get the most of the cloud resources. The IaaS provider is responsible for the structure, operation, and security of the hardware. This is also referred to as the physical environment, which the provider must make available to users at all times. IaaS operators have to contend with the following tasks:

• Establish, maintain and keep data centre infrastructure up-to-date
• Protect the data centre against external influences
• Provide computing power (CPU, working memory) and storage space
• Provide server and network structures as well as databases
• Create a virtualisation environment that customers can use to access the IaaS resources provided
• Provide software that enables customers to control and administer the virtualised IT infrastructure

Based on these hardware and software structures, customers can then assemble and manage their own small data centre. However, this includes not only organising and using the logical environment, but also taking security measures to protect the virtualised IaaS resources used. The tasks that the customers need to carry out can be summarised as follows:

• Choose and structure the desired virtual infrastructure
• Install, configure, and regularly update operating systems and any application software required for your own purposes
• Run the IaaS network and configure the firewall
• Protect the operating systems and any other installed software (also applies to own applications, of course) using security software
• Encrypt data and data connections
• Set up authentication mechanisms, identity controls, and access controls

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Depending on the way the service is provided, there are basically three different types of IaaS solutions:

• Public IaaS

• Private IaaS
• Hybrid IaaS

Public IaaS is the basic version of the practical cloud service. The term “public” is derived from the fact that the resources offered are generally shared by all the provider’s customers and accessed via the internet. However, sharing hardware leads to conflicts, as all resources are virtualised and detached from a specific computer.

The concept of private IaaS differs from the actual idea of infrastructure as a service in that it is not an external service provider, but an in-house IT department that provides the supplies and leases the resources. This way, the company benefits from the possibilities of IaaS technology without losing control over data and security. However, this means that the scalability is no longer flexible. In addition, the company itself is responsible for the physical environment.

Hybrid IaaS is a solution that combines public and private IaaS. With this solution, the resources are obtained both from an internal service provider and from an external provider. This makes it possible to manage sensitive company data on your own while the scalable external resources are used for other purposes.

Infrastructure as a service isn’t suitable for every company or every purpose. For example, if you are just looking for some storage space, an online storage service is more likely to offer lower prices than an IaaS provider. The same applies to selecting a suitable provider for hosting simple company websites – classic web hosts usually have much cheaper offers available.

The following table shows in which business scenarios infrastructure as a service is more than just a simple alternative to classic hosting scenarios or your own local infrastructure:

Infrastructure as a service solutions are packed with many advantages: First and foremost, outsourcing the required IT resources saves the purchasing, installation, and managing of expensive hardware (with the exception of private IaaS). In addition, you always have an eye on running costs thanks to the industry-typical billing according to what you use and can therefore economise efficiently with the available budget. Added to this is the flexible scaling of resources in both directions, which makes it possible to adapt the IaaS environment to current business conditions.

While transferring responsibility on a physical level saves a lot of costs and effort, it also has a decisive disadvantage when it comes to infrastructure as a service: As a user, you have no influence whatsoever on the availability of the service or on the functionality of the individual components. When it comes to security and data protection, you aren’t in charge here either. Another disadvantage of IaaS is that although changing the provider is possible at any time, it’s quite tedious to do due to missing standards and inconsistent interfaces.

The most important advantages and disadvantages of infrastructure as a service at a glance: