In the DevOps world the knowledge of Containerization and Virtualization, and their differences is crucial for every engineer. Although they both function at various stages of the computing stack and have unique technological characteristics, they are the same technologies that we use to install and manage applications.
With this article we are going to point out 10 differences between Containerization and Virtualization every DevOps should know. But before that let’s look at them individually.
The idea of virtualization is to create a virtual version of server, operating system, program etc. The purpose of virtual machines is to use them to run some applications in isolated environments, without affecting the main hardware.
To create a virtual machine, you’ll need a Hypervisor, or so called Virtual Machine Monitor (VMM). It allows a computer (or bare metal) to work many virtual machines, and creates virtual hardware for them like CPU, RAM, Storage etc. There are 2 types of hypervisors: bare metal and hosted.
For the bare metal type, the hypervisor is laying directly on top of the hardware. The hosted hypervisor is laying on top of the host operating system. Here are main differences between between the two types:
On the other half, containers are packaged applications, codes and dependencies that can run quickly and reliably on every server, or virtual machine.
They are lightweight, self-contained, and include everything you need to run an application: code, runtime, system tools, libraries, and settings.
The most famous containerization tool is Docker. Here you can check our blog Containerization with Docker. There are no hypervisors, only docker daemon service that takes care of containers. Docker uses client-server architecture, so the daemon pulls, builds and runs docker images from registries or locally based ones.
The operating system is the first—and most likely—difference between virtual machines and containers.
Using a hypervisor, virtualization entails executing all physical resources, including the operating system (OS), on a virtual machine (VM). With a separate OS instance, every VM runs on its own. This implies that we can run multiple virtual machines (VMs) on the hypervisor, each running a separate operating system.
In contrast, containerization doesn’t have an Operating system on its own. Containers have all the needed dependencies and packages isolated but without the need for a separate OS instance. They are using the host operating system they are running on.
Virtual machines are resource-intensive because, as we noted in the previous difference, hardware resources like OS, RAM, CPU, storage, etc. are reserved.
Contrarily, containers are lightweight. They share the host OS kernel and use fewer resources, making them more efficient in terms of memory and storage utilization. They have no predefined resources by default, they are using as much as they need to exist.
The isolation level of VMs is very good, they are ensuring security and preventing interference between each other.
Containers have lower levels of isolation because they need the host OS kernel, even though Docker security features have significantly enhanced container isolation.
As we mentioned a few times, containers are lightweight and have reduced overhead, which means they offer superior performance compared to virtual machines.
Boot time for containers is almost instant, facilitating rapid scaling and deployment of applications. Virtual machines, with their complete OS instances, take longer to boot and consume more resources.
This sounds logical, after everything we said already, but there is a deployment difference. Virtualization uses a hypervisor to create virtual machines.
In containerization we use server templating tools like Docker (docker daemon), or orchestrating tools like Kubernetes to deploy our containers.
This difference comes again from the fact how we are deploying containers and vms, also the OS they are using: Virtualization has a strong security model, isolating VMs from each other and the host system.
Because containers are using the host OS, they rely on the host OS’s security features, although additional security measures can be implemented using tools like Docker Security Scanning.
However, both containerization and virtualization continuously evolve to address security concerns and vulnerabilities.
Virtual hard disks (VHDs) or virtual machine disk files (VMDKs) are used by the majority of virtual machines as a data storage medium. The files for them are large, most of the time, and should reserve some storage space on the host or bare metal.
Containers are using storage drivers to manage storage. Here the storage is typically lighter and portable, the images and data are stored in layers, making them easier to distribute and manage.
Virtual machines have a virtual network interface card (vNIC) and a private IP address attached to them, which provides full network stack isolation.
Meanwhile, containers share the host machine’s network stack. There are network namespaces and bridging containers used to isolate networks between each other. This makes them perfect for applications requiring complex networking setups.
Snapshot and Backup
Virtual machines have impressive backup and snapshot abilities. We can capture the VM’s current state and restore it when needed.
Containers also provide snapshot support, however, given their statelessness, container image and data savings often constitute the primary backup solutions.
Due to their lightweight nature and rapid deployment, containers have proven to be optimal for cloud-native applications, microservices architecture, and DevOps practices.
Virtualization, on the other hand, is best used when running various operating systems on a solitary machine is needed, making it advantageous for varying OS environments.
The dynamic world of IT relies on a diverse toolkit that includes virtualization and containerization. Both technologies have their unique use cases and advantages that depend on factors such as resource efficiency, isolation level, and portability.
Understanding of their technical differences is crucial for every DevOps Engineer and System Administrator. Virtualization and containerization will probably always coexist as technology advances. Selecting the best technology for a given situation is crucial to guaranteeing maximum efficiency, scalability, and resource management.