Containers vs Virtual Machines – What’s the Difference ? (Pros and Cons)
Containers vs Virtual Machines – What’s the Difference ? (Pros and Cons).The growth of application So are container’s the same as virtual machines or do they differ?
If containers are disposable can you apply them alongside persistent storage? And to they assist server virtualization? In this blog post about Containers vs Virtual Machines we will see how virtual machines (VMs) are different from containers.
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The motivation for containers and virtual machines dates back to the days of bare metal application servers. These, typically, were beefy physical machines, each running a single application or service.
Getting one up and running was a laborious task: building the system and configuring the software could take hours. Testing and fine tuning your system could add even more hours, if not days.
And when all that work was done, systems administrators would often find that the resources of their big, expensive machines remained underused.
Containers and virtual machines solve all these problems. They provide the means to optimize resource usage and provide the portability and automation necessary to eliminate development bottlenecks and speed up production.
At the core of both is the concept of virtualization.
With our blog post Containers vs Virtual Machines – What’s the Difference ? Let us introduce what virtualization is.
Virtualization and its benefits
Virtualization, in a nutshell, simply means using software to create a virtual version of something, like hardware or an operating system.
It is done through a software called a hypervisor, and what it does is it connects directly to your hardware so that your system is split into separated and secure environments called virtual machines. The hypervisor can separate machine resource (memory, storage , CPU) from the hardware and distribute it.
Virtualization features
Virtualization has some attractive benefits:
Faster provisioning
Containers and virtual machines can be created from scratch in a matter of minutes. Once the virtual machine or container has been configured, each can be saved as a template. The entire provisioning process can then be automated.
Improved business continuity
Both containers and virtual machines support external connections and links. This makes it easy to create multiple, redundant versions of each to eliminate downtime or other types of service disruption.
Simplified management
Automated provisioning makes it easy to enforce global policies (e.g. security policies) across all instances of a virtual machine or container.
Reduced costs
Virtualization reduces upfront hardware costs as well as operational costs. Since virtualization dramatically reduces the need for physical space per machine, it also delivers reduced power, cooling, and hosting costs. (This applies to containers too, since they can be run on virtual machines.)
Increased productivity
The entire provisioning process is now faster, which means IT staff have more time to focus on mission-critical tasks.
Better disaster recovery response
Simpler data center management
What is a Container?
Consider the applications you use every day. Each one is installed on top of the operating system and requires some of the operating system’s libraries and other components to function. A container is a software unit consisting of the application and the necessary operating system components, nothing else.
Containers also enable microservice architectures, where the monolithic application is composed of smaller services. The benefit here is that these services are easier to maintain individually, provide the opportunity for different technology stacks per microservice, and can be scaled individually as required.
Key among the benefits of a container is that it allows a separation of infrastructure requirements from the application environment, which eliminates OS configuration overhead, and makes it easy to run your fully configured application in different environments.
Container use cases
- Multi-cloud.
- Automation– API controlled for CI/CD process.
- Microservices.
Features of Containers
Platform agnostic
Containers can run anywhere, on virtually any operating system. Run them on your home computer, your organization’s servers, or in the cloud.
Easy installation
Container software like Docker makes it easy to install and run containers without much prior knowledge. Ready to run container images of popular applications are also available from public repositories.
Orchestration
With container orchestration large numbers of containers can be provisioned and linked across multiple hosts using tools like Docker Swarm or Kubernetes.
Networking
Containers can be linked to each other at runtime. But they also support networking that allows communication between containers and external workloads. Here the container behaves like a virtual machine.
Community support
In recent years containers have surged in popularity, giving rise to volumes of freely available documentation that help simplify complex actions. You’ll also find massive community support across various different platforms.
What is a Virtual Machine (VM)?
Unlike containers, any number of applications can be run on a virtual machine – resource permitting, of course, since it is for all practical purposes an independent system running its own OS.
Where containers rely on OS virtualization, virtual machines rely on hardware virtualization. This hardware abstraction is provided through software called a hypervisor which is either installed on top of the operating system (Type 2 hypervisor or Hyper-v) or installed directly on the hardware (Type 1 or ‘bare-metal’ hypervisor).
As with containers, many virtual machines can be installed alongside one another, and interact in the same way bare metal machines do.
Features of virtual machines
Scaling
Virtual machines can be scaled as necessary by adding more compute power, or by adding other virtual machines that help carry the workload.
Full hardware virtualization
Virtual machines provide the added benefit that they can virtualize almost any type of hardware. Run WinAmp on a Windows 98 VM playing songs from your dad’s old CDs using your computer’s DVD drive. (You probably wouldn’t, but you could.)
Desktop mobility
When thinking of a cloud based virtual machine, a CLI-based system comes to mind. However it is entirely possible to run a desktop GUI on your cloud based VM. This facilitates mobility and local hardware independence.
Virtualize everything
Not so much a feature of virtual machines, but rather of virtualization in general, is the fact that storage and networking components can also be created. This makes it possible to run an entire infrastructure on any hardware platform that can support it.
Community support
Virtual machines are popular and are here to stay. As with containers, extensive documentation, literature, and thriving online communities simplify the learning curve.
Now it is time to compare Containers vs Virtual Machines – What’s the Difference ?
Containers vs Virtual Machines - Pros and Cons
Resource Usage
Containers
Out of the box, containers have no resource constraints. This means a container could potentially use as much memory, processing power, and storage as the host OS allows. As such, resource constraints have to be specified explicitly at runtime.
Virtual machines
Hardware abstraction is based on the actual resources of the host system. Resource upper limits are defined when the virtual machine is created, putting control of processing power, RAM, and storage in your hands.
Hypervisor / virtualization software packages also employ a reservation mechanism, which checks that the upper limit resources are available before the machine is started. If these resources aren’t available, the VM won’t start.
But virtual machines also run the risk of inefficient resource usage, when available resources far exceed operational or system requirements.
Graphical User Interface
Containers
Containers are generally used for applications run and managed via the command line. As such a graphical user interface (GUI) isn’t included by default. But that doesn’t mean it’s impossible – it might just take a little extra elbow grease to get your GUI-based application containerized.
Virtual machines
Since the purpose of a virtual machine is to act as a standalone system, the choice of GUI – desktop environment or applications – is entirely up to you.
Portability
Containers
Containers are made to be lightweight and portable, which means they can easily be copied from a hard disk to a USB flash drive, or quickly backed up to cloud storage.
Virtual machines
It’s an entire operating system along with all additional user and system data, which means you’re looking at one or more files that total a few GB in size. As such virtual machines are portable but will take significantly longer to move from one location to another.
Provisioning
Containers
With orchestration software containers can be created, started, and otherwise managed in seconds. The whole management process can be automated, which means you can easily deploy tens, hundreds, or thousands of containers at the push of a button.
Virtual machines
Given their size and complexity, automated virtual machine provisioning is a little slower than containers, but still blazing fast compared to the manual assembly and configuration of a bare metal server. As with containers, automation can be based on stored templates, which simplifies policy enforcement and overall management.
Security
Containers
Containers share the host OS kernel. Vulnerabilities in the OS kernel will leave the container exposed. Likewise, vulnerabilities in the container could allow attackers access to the OS. As such both the OS kernel and the container must be secured.
Virtual machines
Virtual machines provide slightly better protection for the host system. Should your virtual machine get hacked, the attacker will have to get past your virtualization software to gain access to the host system. Unlike OS exploits, virtualization software vulnerabilities are few and far between, but they have been known to exist.
OS Dependency
Containers
Can you run Windows containers on Linux and vice versa? Short answer: no. Containers rely on the resources and drivers of the underlying operating system which negates interoperability between Windows and Linux. However, a Linux based container can be run on other Linux distributions, usually without a hitch (note: it always helps to keep your fingers crossed).
Virtual machines
Virtual machines are a bit more flexible. Moving a virtual machine from Windows to Linux is doable, typically when the same virtualization software is available for both platforms. It is also possible, but slightly more complex, to move a virtual machine between different virtualization software distributions (e.g. from VirtualBox to VMware).
Great job. We have learned Containers vs Virtual Machines – What’s the Difference ? Let’s summarize.
Containers vs Virtual Machines - What's the Difference ? Conclusion
The difference between a container and a virtual machine (VM) is that containers do not run on their own operating systems but use the operating system they are installed on. Containers benefit in reducing management overheads and they are lighter weight and more portable than VMs. So the conclusion is that virtual machines and containers differ in several ways, but the main difference is that containers provide virtualization, so that multiple workloads can run on a single OS instance. With VMs, the hardware is being virtualized to run on multiple OS instances.
The use cases for containers and virtual machines are too different to recommend one over the other. Containers are ideal when you want to run a single lightweight application which optionally requires extensive portability, whereas virtual machines are used to simulate the infrastructure needed to run an operating system. Running a virtual machine for your containers is also an option, with the virtualization software providing an additional layer of protection between the container and your host system.
Multiple virtual machines enables business to lower costs and improve DevOps efficiency. Virtualization helps with reducing server waste and limiting carbon footprint.
