Containerization vs Virtualization

Rapid developments in technology are changing the hosting landscape, and part of this transformation includes a vital distinction we need to be aware of between containers and virtual machines or rather containerization vs virtualization. Both are important means of storing data. While both terms are common in use, they are often confused. 

What is the difference between virtualization and containerization, which is better? This debate has many sides and many benefits. It's important to know which method is best for your application needs, especially if you're looking to run your applications in the cloud. 

We'll discuss the main differences between containerization and virtualization as well as the pros and cons of both.

The difference between virtualization and containerization

To understand the difference between containerization and virtualization, it’s best to begin by understanding the basic meanings of these terms.

What is virtualization?

The word virtualization is derived from the term virtual machine. The basic meaning of a virtual machine is simply a machine that exists in virtual form  i.e. it is not physical, not tangible. But to be able to have a virtual machine, you need a physical machine. The physical computer is known as the host as it is the one that houses the virtual machine.

Virtualization therefore is the creation of a virtual version of a physical computer. The virtual computer depends on the resources (CPU, storage and memory) of a physical computer.

What is containerization?

Containerization is derived from the word container. A container, as we know it in ordinary use, is an enclosed object that is used for holding and transporting something. In technology, a container is a standalone unit that is used for holding and transporting applications. 

Containerization therefore is the process of packaging everything that is needed to run an application into a single self-reliant unit that can run anywhere. 

Further reading: What is Containerization

The main differences between containerization and virtualization

Now that we have an idea of what is containerization and what is virtualization, it’s a good time to find out the key virtualization containerization differences.

Here they are:

Separation from host server OS

The major difference between virtualization and containerization is how they separate the host server OS from the programs that run in them. While virtualization uses a hypervisor to detach and virtualize the OS into multiple «operating systems», containerization uses a container engine to isolate the programs from the OS. This ensures that a container will not wreak havoc on the host OS. Since each container is isolated, it is possible to install and uninstall its own software without affecting the other containers or the main OS.

Operating system

Virtualization lets you run multiple operating systems on the same hardware, but the guest OS (virtual machine’s operating system) doesn't have access to the underlying OS. Containerization on the other hand  encapsulates each application in its own operating environment.

Booting time

Containers can get up and running in seconds. A virtual machine on the other hand must first boot up the entire virtual system. Since each VM includes a complete copy of an operating system, it takes a lot of resources to boot up. Containers on the other hand have no need to replicate OS code, and are considerably more lightweight than VMs.

User privileges

Containers can be run by non-root users. Virtual machines need to be started by root users. For example, you can run a MySQL server in a container as user 'postgresql'. This gives the non-root user the same privileges as a root user, but the only difference is the container engine.

Running environment

Containers run on software while virtual machines are created on hardware. Basically, virtual machines’ run on a single physical machine. A container requires only a single operating system to run, while each VM requires an OS of its own i.e. a full boot process

Summary: Top differences between containerization and virtualization 

Here is a summary of the top fundamental differences between containerization and virtualization;

Advantages and disadvantages of containerization over virtualization

Containerization offers a wide range of advantages and disadvantages over virtualization. Here are the top advantages and disadvantages of containerization over virtualization:

Advantages of containerization over virtualization

The advantages of containerization over virtualization are overwhelmingly abundant, and here they are;

Portability

Perhaps the most critical advantage of containerization over virtualization is the fact that containerization makes it possible for businesses to keep their software applications portable by allowing developers to use them in more environments.  Containers are much easier to transfer from one machine to another.  And because of this, developers can transfer them from one platform to another without worrying about compatibility issues. In contrast, Virtual Machines require a copy of the host operating system and are larger.

Deployment

With containers, developers don't need to worry about where an application will be deployed — today it might run on a private cloud and tomorrow on a public cloud. They are ideally suited for DevOps pipelines and automated applications. Moreover, they allow for continuous deployment and integration.

Less resource consumption

By utilizing a standard operating system kernel, containers use far fewer resources than virtual machines.  Compared to virtual machines, containers are much smaller. And because they use only a portion of the host machine's operating system kernel, they use significantly less resources. Containers also start much faster compared to virtual machines.

Scalability

Containerization scales better than virtualization, which limits the number of instances per server or cloud instance. Furthermore, because the software is isolated, any potential bugs or errors cannot affect other containers. With containerization, developers can define security permissions and automatically block unwanted components, ensuring that applications are running in the correct environment.

Reduced runtime 

Containers reduce runtime. Because they run on an operating system, they start up instantly. This is great news for software development teams, as virtual machines require plenty of time to boot up. This means virtual machines are often slow to start, and containerization speeds up that process. 

Memory efficient

Containerized workloads are much more memory-efficient than virtual machines. This is because the container does not need to run a full copy of the operating system. Also, containerized workload systems can judge when they need to scale out by copying and removing containers based on their memory requirements. This gives them the flexibility to run many applications on a single server.

Shareability

Unlike virtual machines, container images can be easily shared between multiple servers. Virtual machines can't leverage application sharing hubs or other sharing services.

Disadvantages of containerization over virtualization

While the advantages of containerization over virtualization are obviously enormous, it's also important to consider the following disadvantages of containerization over virtualization.

Compatibility

Although containers are more efficient than VMs, they lack bare-metal performance, and aren't well compatible with graphical applications.

Vulnerability

Containers share OS components, kernel, and libraries. This makes them prone to vulnerabilities.  Ideally, containers and hosts should have security mechanisms in place that detect and prevent attacks.

Shutdowns

Once a container is done executing a task, it shuts down and all the data inside is deleted. The only way to get the data to remain within the host server is by using data volumes to save it, which requires considerable manual tasks to configure and provision. 

Containerization vs. Virtualization: Conclusion

A common question when deciding between virtualization and containerization is which one is better for your organization. As we have seen, there are advantages and disadvantages to both approaches. 

A choice between the two will ultimately depend on what you want to achieve. If you are looking for a virtualization alternative that eliminates the overhead of managing VMs and rides on the host OS, then containerization could suit you better. Otherwise containers are more efficient for ephemeral use cases, such as web applications, as they share the same OS kernel.

Containerization and Virtualization: FAQ

Is containerization better than virtualization?

This depends on your needs. Containers are better for applications that are ephemeral in nature while virtualization is a common choice for demanding applications that require the complete functionality of an operating system. 

It’s worth noting that the use of containers reduces the number of inconsistencies. Because they are isolated from the host OS, the operating system is not impacted by the application's failure. Containers can also be moved and shared between the different hosts. 

What is the difference between containers and VMs?

Containers are essentially isolated or independent that run on a single server and host OS. Because they run on a single host, they share the same kernel, shared libraries, and other systems. They're great CI/CD implementation and collaborative development, but they are not as secure as VMs.