Though Docker containers are sometimes referred as ‘light-weight VMs’, they are not VMs (virtual machines). Both serve different purposes, and hence one cannot replace the other.

Their underlying architecture is what differentiates Docker from Virtual machines. While VMs are based on server virtualization technology, Docker uses container virtualization. 

Today we’ll discuss the major differences between Docker and Virtual machines and see which one suits your business purpose more, based on these features.

1. OS support

The basic architecture of Docker containers and Virtual machines differ in their OS support. Containers are hosted in a single physical server with a host OS, which is shared among them.

Virtual machines, on the other hand, have a host OS and individual guest OS inside each VM. Irrespective of the host OS, the guest OS can be anything – either Linux or Windows.

Docker containers are suited for situations where you want to run multiple applications over a single OS kernel. But if you have applications or services that need to run on different OS flavors, VMs are required.

Sharing the host OS between the containers make them very light and helps them to boot up in just a few seconds. Hence, the overhead to manage the container system is very low compared to VMs.

Docker Vs Virtual machine – Architecture comparison

2. Security

In Docker, since the host kernel is shared among the containers, the container technology has access to the kernel subsystems. As a result, a single vulnerable application can hack the entire host server.

Providing root access to applications and running them with super user privileges, is therefore not recommended in Docker containers because of the security reasons.

On the other hand, VMs are unique instances with their own kernel and security features. They can therefore run applications that need more privilege and security.

At Bobcares, we implement additional security measures such as SELinux and AppArmor in Docker to secure the containers and to prevent them from cracking each other or the host kernel.

3. Portability

Docker containers are self-contained packages that can run the required application. Since they do not have a separate guest OS, they can be easily ported across different platforms.

The containers can be started and stopped in a matter of few seconds, compared to VMs, due to their light-weight architecture. This makes it easier to deploy Docker containers quickly in servers.

VMs, on the other hand, are isolated server instances with their own OS. They cannot be ported across multiple platforms without incurring compatibility issues.

For development purposes where the applications have to be developed and tested in different platforms, Docker containers are thus, the ideal choice.

4. Server density

Docker containers only contain the application for which its intended to work for. So, they are light-weight and are helpful when you need to run a lot of identical applications in a single physical server.

But if you need to run multiple applications on server instances with a variety of OS flavor support, then you’ll need VMs. Virtual machines contain the entire OS and its supporting binaries, making it heavier.

Since the number of VMs that can be hosted on a physical server are limited in count compared to Docker containers, the server density would be lesser with VMs, compared to Docker.

This makes Docker containers more suitable for cost-effective application hosting such as WordPress or Magento hosting, while VMs can be used for providing customized hosting services.

5. Performance

Docker and Virtual machines are intended for different purposes, so its not fair to measure their performance equally. But their light-weight architecture makes Docker containers less resource-intensive than the virtual machines.

As a result, containers can start up very fast compared to VM, as the latter has to load an entire OS to start. Resource usage also varies among the two.

In containers, the resource usage such as CPU, memory, I/O, etc. varies with the load or traffic in it. Unlike the case of VMs, there is no need to allocate resources permanently to containers.

Scaling up and duplicating the containers is also an easy task compared to that of VMs, as there is no need to install an operating system in them.

To summarize..

The key features of the Docker containers and Virtual Machines can be summarized as follows:

Comparison of key features – Docker Vs Virtual Machines

These key features determine the business suitability of Docker containers and Virtual Machines (VM). Based on that, we can list down the applications for them:

Business applications – Docker vs Virtual machines

Docker containers:

Software application development 

Testing software applications in multiple platforms

Application hosting services such as WordPress or Magento hosting

Virtual Machines (VMs):

Secure hosting services for multiple businesses

Server instances that require varied services and applications to run together 

Businesses that require multiple OS support for their applications

As we discussed here, Docker and Virtual machines do not serve the same purpose and so its not possible to replace one by the other.

At Bobcares, our engineers assess the business requirements of our customers first and then setup the best virtualization infrastructure for them to suit their purpose.

Our 24/7 expert teams manage the servers and virtualization systems for webhosting companies and help development businesses optimize their DevOps using Docker containers.

If you’d like to know how to manage your server resources efficiently for your business purpose, we’d be happy to talk to you.