Container-based technology Docker enables its clients to easily create and deploy applications. Due to developments in cloud infrastructure, virtual machines have become the norm in IT departments at many major companies. However, Docker has come onto the scene as a lightweight, inexpensive, and scalable alternative to virtual machines.
But how are Docker and virtual machines different? How do they complement each other in terms of building cloud applications?
Below, we’ll answer these questions and explain the main differences and similarities between these two types of virtual application hosts.
What Is Docker?
Docker is a platform as a service (PaaS) that stores software in what it refers to as containers. These can be used to store any application in the hybrid cloud. Using containers, only the operating system of a given computer is made virtual.
Every individual container shares the same host operating system (OS), along with system resources like libraries and other applications. As the OS resources are shared, the servers can run multiple applications using only one OS installation. This reduces the need to replicate operating system codes.
Docker has introduced modifications to Linux containers to make them compact and pliable. They are the tool that allows Linux applications to be effectively shipped and deployed.
Containers are only megabytes in size and take a few seconds to start running. In contrast, virtual machines take minutes to run and are larger than Docker containers.
In order to run a specific program, a container must have adequate resources and a catalog that supports the operating system. This makes it possible to install a wide range of applications in a single server using Docker.
What Is a Virtual Machine?
A virtual machine (VM) can be described as a simulation of a computerized system. It allows for programs and applications to be used while appearing as if they are running on another computer.
This is done by sharing the hardware resource of a solitary host server among operating systems and their applications. To virtualize hardware, every virtual machine is required to have the same operating system. A hypervisor is software that virtualizes the server which allows the VM to run.
Many IT departments have adopted virtual machines because they are cost-effective and increase performance. The most popular VM providers are VMware, KVM, VirtualBox, Xen, and Hyper-V.
Docker vs VM: The Most Important Differences and Similarities
Docker and VMs are very closely related. Getting confused between the two is completely normal. To help you tell them apart, we have compiled a detailed list of their differences and similarities.
Operating System Support
The fundamental structures of Docker containers and VMs differ due to their operating system support.
Dockers only have one host operating system, which is shared among other containers. On the contrary, VMs employ both a host OS and a guest OS in every virtual machine. A guest operating system can be a variety of different OS’s, such as Linux or Windows.
In the case of Docker, sharing the host OS between containers means they are lightweight and quick to boot up. This means the cost is extremely low when compared with virtual machines.
Virtual machines are generally used when a server or application is running on a variety of operating systems.
Security
Because host kernels are shared among containers in Docker, the chances of getting hacked increase. In contrast, VMs are highly secure because they use individual kernels to run programs.
Portability
As stand-alone packages, Docker containers can easily run any program. As they do not have guest OS’s, containers can be deployed across a variety of platforms due to their lightweight structure.
However, VMs often incur compatibility problems when they are sent since they run on multiple operating systems.
Performance
It is difficult to compare the performance of Docker and VM, as they are designed for different purposes. Nevertheless, Docker containers use less resources than virtual machines due to their lightweight structure, so they boot faster than VMs. In addition, Dockers vary in how they use resources, but because OS installation is not necessary, expansion and duplication of programs becomes a simple job.
Host OS
In Docker, only one host OS is used, while in VM, both host OS and guest OS’s are used.
Root File System
Docker and VM both have their own root file system. The processes of each VM are different. Similarly, processes in one Docker container cannot be seen by the processes in another.
Virtual Network Adapter
VM has its own virtual network adaptor, and Docker can also get its own virtual network adapter with separate IPs and ports.
Docker vs VM: Pros and Cons
Docker and VM are fundamentally different. Virtual machines and containers play separate, important roles in the virtualization of modern programming.
Since you now know a little about how virtual machines and Docker engines function, let’s discuss the pros and cons of each.
Docker Pros
- No hypervisor. Docker does not have a hypervisor. Instead, it utilizes the same resources as the host OS.
- Easy version control. It allows you to easily change the version control using a built-in control system.
- Image layer system. Docker offers copy-on-write mechanisms in which packages with a unique ID, node server, and application layers are packaged to form a container.
Docker Cons
- Unable to run at bare metal servers. As a consequence of the overlay networking between containers and the host system, dockers can’t run on typical bare metal servers.
- Increased complexity. The additional layering within containers means the development and deployment of programs is affected.
- Lack of isolation. The way kernels are shared between containers can create problems. If there is an error in the kernel, every container will be affected.
VM Pros
- Reduces the need for a physical hardware system. VM admins can easily make use of simplified backups, distributions, and restoration in virtual settings.
- Improves efficiency of operations. The tools provided by VM, make it easy to manage, configure and update across several devices at once.
- Easy software licensing. When it comes to virtualization, there is no need to purchase a license for each of your applications.
VM Cons
- Hogs resources. A VM can hog resources when there is a lot of virtual activity. This happens when the OS is unable to allocate enough resources to keep processes running smoothly.
- Impact on UX. If the user experience is impacted, it can be difficult to identify the root cause when using a VM.
- Requires special knowledge. You must have a lot of background knowledge in virtual machines to be able to use them effectively.
Should You Use Docker or VM?
Docker is a container storage app that isolates applications. It enables the user to run multiple applications with the same host OS and to share underlying resources.
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Docker is increasingly being viewed as preferable to VMs. However, it is important to note that although Docker is often considered more efficient in running applications, it will never fully replace virtual machines.
Advantages of Choosing Docker
- Docker is a cheaper IT management alternative.
- It reduces the size of the snapshots.
- It allows apps to be deployed faster, and simplifies security updates.
- It reduces the amount of code that is needed to transfer, migrate, and upload work.
Advantages of Choosing VM
- All OS resources are available to all applications.
- It has well-established management and security tools.
- It enables consumer-level users to try the new OS.
Both Docker and VM have their benefits and drawbacks. Which one you use will depend on your goals. VMs are a better choice for running applications that require resources from a variety of operating systems.
Docker is the best choice if your biggest priority is to maximize the number of applications running on a smaller number of servers.
In many situations, the ideal IT setup will likely include a bit of both. In the current state of virtualization technology, the flexibility of virtual machines, and the minimal resource requirements of Docker can be a successful combination.
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