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Docker Containers vs. Virtual Machines – Know The Differences

Written by Marius Rimkus
on March 31, 2020

Virtual Machines (VMs) have become the standard for fulfilling cloud infrastructure needs as they are the ideal choice for data centers running cloud services. However, a new technology is generating quite a buzz in tech spaces across the globe – Docker Containers.

Both help IT departments utilize their hardware and software resources to the fullest, providing unprecedented agility and control to organizations.

If you’re deliberating between a Docker containers and Virtual Machines for your cloud service, it is essential to have a sound understanding of these virtualization technologies.


What Are They?

These are entirely different technologies and have distinct operational abilities. Here’s a more comprehensive definition of both, followed by a deeper look in the differences and how can they affect your decision.

Virtual Machines

A virtual machine (VM) emulates your computer system. It enables the running of several separate computers on a single computer’s hardware. The operating systems and their applications share the hardware resource of the host server.

Each Virtual Machine requires its operating system, with its hardware virtualized. A hypervisor runs the hardware, software, or firmware that virtually monitors the VMs.

The hypervisor sits between the hardware and the VM and is crucial to virtualize the server. 

VMs utilize many system resources: each VM runs on a virtual copy of all the hardware. This adds up to the RAM and CPU cycles.

Docker Containers

Docker is a container-based technology that only virtualizes the operating system. The Docker container sits on top of its physical server and the host operating system (most often Linux or Windows.)

Each container in the system shares the host operating system kernel, including the binaries and the libraries: the components being read-only. This dramatically reduces the need to reproduce operating system code, unlike with VMs.

Moreover, this means container servers can run multiple workloads on a single operating system. Docker containers take up only a couple of megabytes and have faster loading times.

Additionally, a docker container lets create a consistent, portable operating environment for developing, testing, and deploying applications.


Docker Containers Vs. Virtual Machines

Here’s a quick rundown of each and their capabilities:


  • Docker containers can start-up in just a few seconds
  • They operate under the execution engine
  • Docker containers don’t need space to virtualize, and take up less memory
  • Docker containers are more susceptible to security threats as systems cannot be isolated
  • Only a single, containerized image is required to deploy on all platforms
  • It has an intricate usage mechanism that consists of a third party and its own managed tools

Virtual Machines

  • VMs takes a few minutes to initialize
  • They run under the hypervisor
  • VMs require the entire operating system to be loaded before you can start the surface – considerably less efficient
  • The possibility of Interference is minimal due to the virtual machine’s isolation mechanism
  • Comparatively lengthy deployment time as separate instances are needed for execution
  • Tools offer ease of use and are simpler to operate with

The core differences between VMs and Docker containers are more apparent when taking a look into their OS support, the security they provide, portability issues, and performance reviews.

Operating System Support

The operating system support of a VM and a Docker Container are worlds apart:

A VM has its guest operating system above its host operating system, which makes the virtual machine itself, very heavy. A Docker container, on the other hand, shares the host operating system between other containers – which makes them extremely lightweight.

Therefore, managing the docker containers is easier in comparison to VMs. VMs are best suited for when you have applications that need to run on different operating system flavors. But, the containers are equipped for situations where multiple applications need to be run over a single operating system kernel.

System Security

VMs don’t share operating systems, and the host kernel is isolated. Consequently, they offer more robust protection than docker containers.

Containers pose numerous security risks as they share the same host kernel. Docker containers share resources between the kernel subsystems. So, in the likelihood of a cyberattack, hackers that manage access to one container, can exploit all of them in a cluster.  

With VMs, the hypervisor restricts the resource usage in Virtual Machines, and users don’t have direct access to them.


Unlike VMs, Docker containers don’t rely on guest operating systems, and so they’re incredibly portable and can be ported to a different OS and started immediately. Because of their size, porting VMs to a different system poses a variety of compatibility issues.

Docker containers can run applications in any environment; because of their lightweight, they can be initiated and stopped in considerably less time than VMs, which need to load the entire operating system to start.

In terms of developmental purposes, where applications need to be tested on different platforms, Docker containers present themselves as the ideal choice.

Performance Review

Comparing Docker containers and VMs in terms of performance may be unfair as both functions to serve different purposes. That being said, Docker containers being so lightweight means they are faster than VMs.

The Docker container’s resource usage relies on the traffic or the load in it.  

Unlike VMs, Dockers don’t need to be permanently allocated to them. Duplicating and scaling containers is effortless when compared to VMs since entire operating systems don’t have to be installed.


The Right Choice For You

There’s no doubt that Docker containers are gaining popularity. That being said, they aren’t going to replace VMs entirely. They’re both complementary tools for differing workloads and usage.

In a production environment, VMs are indefinitely the more viable choice as they run on their own dedicated operating systems, without posing a threat to the host computer. On the other hand, Docker containers are more flexible and the go-to choice for testing out applications since they provide different platforms.

Additionally, Docker containers have low overheads as they are compatible with sharing single kernel and application libraries. Consequently, many companies prefer them as deployment is much faster, and running microservices is relatively easy.

However, firms that prioritize security find VMs the ideal choice.

Still unsure of what is compatible with your cloud system? Cherry Servers provides cost-effective cloud infrastructure on-demand so you can scale your business. Get in touch with us today to learn more about these and other services!