«The Cloud» does not exist

What is cloud anyway? And why are not all clouds the same? An overview to create clarity.

The topic of the cloud is currently on everyone’s lips again, and decisions are pending in many places. Clarity is essential for assessing the impact on individuals, the economy and society. That’s why we’re starting a small series today that aims to create understanding and clear up misunderstandings.
This text is also available in German 🇩🇪.

Don’t lump everything together

“The cloud is just someone else’s computer,” goes the saying. Just as we don’t lump all our own computers together, but distinguish between mobile or laptop, home or work computer and many others, we shouldn’t lump all clouds together either.

Because these cloud computers can also be equipped very differently with hardware, software and services. On the one hand, this gives them very different properties. On the other hand, different mechanisms are also required when it comes to building or applying a secure, high-performance or reliable cloud from “any cloud”.


What criteria can we use to differentiate the cloud?

From a technical point of view, we can roughly make a three-way division:

But we can also look at the level of abstraction, aka the amount of service that comes with the offer:

The three main aspects of cloud applications are storage (green), processing (compute, blue) and communication (network, red). With increased level of abstraction (further away from the hardware), the three aspects (and thus the colors) often fuse. (Download as SVG, PDF, PNG).
(For those preferring a table or using a screen reader: This drawing also exists as a table.)
How to read this figure: 1. Block Storage focuses on storage; the service offers a low level of abstraction (“bare metal”, the hardware is at the provider’s, but the customer is responsible for configuring it and installing even the most basic of software). 2. SaaS focuses mainly on software and running it; the service comes with a high level of abstraction (the provider takes care of the number and configuration of hardware; the customer has no say in this, but also—ideally—will not notice if hardware fails).


There are no strict borders between the categories, in fact, the transition is very smooth, making differentiation hard. This is probably why everything is often simply thrown into the “Cloud!” basket, which in turn also simplifies marketing.

To structure the cloud space, we start using to some exemplary products and categories. (Again, these categories are by far not as clearly separated from each other as the graphic suggests; they rather float like clouds themselves).

CDN servers are closer to the users and can therefore reduce traffic. For this, they need to decrypt the traffic, posing as the company web server. In turn, they have access to all data. The company web server is still connected to the Internet, otherwise the CDN could not use them as back-end servers; they are just less publicly announced.

Reasons for cloud applications

Why does someone rely on cloud instead of their own computers? Here are a few possible reasons:


Not everything sold under “cloud” should be lumped together, but decision makers should know the characteristics of the services they subscribe to, including the associated risks and side effects. Only then can you ask the right questions and make sound decisions: For yourself, for the company, or for our entire society.

Cloud decisions always depend on where the cloud fits into one’s own processes, but also on how much IT know-how already exists within the organization. Depending on this, it is also possible to achieve a large part of the advantages of the cloud in-house with standardized tools (open source or commercial) and then retain one’s sovereignty and benefits, both within and outside of IT.

Anyone making decisions about cloud should, of course, first and foremost know their needs or requirements. But this actually applies to all decisions, even if this is most easily forgotten in the IT sector.


Further reading

Tabular overview

Level of abstraction Storage Computing Network
low: „bare metal“, the customer can see and control many aspects of the hardware, but has to deal with them as well. Block Storage etc.: iSCSI, Amazon S3, … IaaS/virtual machine: Almost like your own computer, but it is located at your provider’s and can be grown and shrunk on demand. Proxy/VPN:
Your data packats will be forwarded more or less directly.
medium Cloud data base:
The DB server’s machine itself does not have to be administered. However, if you make a mistake, such as not setting a DB password, anyone around the world is able to access your data.
Some things come pre-setup by your provider, intended for a specific use case. The customer still has to configure a few things.
CDN/Content Delivery Network:
Your entire web traffic will be processed intelligently and optimized.
high: „full service“, the provider tries to provide an all-inclusive offer. The customer does not see the underlying hardware and has no possibility to chang or optimize it or configure it for specific applications. File Hosting:
Users can save entire files, view them in the web browser, and share them with other users.
The provider has already set up things for the customer, such as a Web CMS. The customer can start adding content immediately.
„Serverless“ Computing (still runs on servers, despite the misleading marketing name): User-defined functions will process the network requests; includes aspects of computing, and therefore reaches far into the computing sector in the illustration.
Cloud applications „Office“ applications:
Storage, compute and networking are provided as a fused service.
A (simplified) tabular presentation of the introductory graphic under the “Differentiation” heading.

Additional services and duties

If you use a cloud, you will need additional administrative services. These services themselves are often part of the cloud service offering, but lie outside of the table:

Even if everything seems to happen automatically, some duties (most notably the overall responsibility) always remains in the hands of the customer.

Image source

The title image is a remix based on two images by Simon Eugster: Left, Leuchtende Stratuswolke (CC BY-SA 3.0), right Cirrus Uncinus With Plane (CC BY-SA 2.0-de)

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