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: