The Differences Between Virtual Machines and Containers

The Differences Between Virtual Machines and Containers

In today’s online world, the use of cloud services are present almost everywhere, with “virtualization technology” being the key factor to enabling these services. In general, cloud applications are provided by the Virtual Machines (VM), which are hosted on physical servers themselves (Hosts). After final release by the Development Team, the applications are handed over to the Operation Team and are run on the VM.

The Benefits of Choosing a VM

Why would you choose a VM over a physical server? Here are three main benefits of many:

  1. Each application is independent and can work with different operating systems or environments
  2. Resources (CPU, RAM, Storage) managed by the Hosts can be assigned to the VMs efficiently through the application
  3. Through Hypervisor, the VM is able to take Snapshots in case of need for disaster recovery

The Popularity of Containers

However, technology cannot always satisfy everyone. The industry is beginning to think that VMs will occupy too many resources, and so the popularity of Containers has risen. Unlike VMs, Containers do not simulate hardware resources, meaning they do not use Guest OSs. In short, a Container is a virtualized in its own application and corresponding environment. There are even more benefits to containers, as of which only a few are detailed below:

  1. An image of a VM can range anywhere from a few gigabytes to tens of gigabytes, whereas a Container typically only takes up a few hundred megabytes. This lightweight feature makes image file management and startup/shutdown processes of applications much faster.
  2. As long as Docker is installed on the physical server, Containers are easily transferable. Containerized applications can be run normally regardless of the host OS.
  3. Containers have immutable functionality, meaning that as long as the application is operating normally, there is no need to worry about application environment errors
  4. Through Docker, the development, management and operation of Containers are very simple. The implementation of DevOps (Development + Operations) solves the common problems of development and maintenance in this environment.

With this being said, it seems that Containers have their place in future markets and are set to replace all applications of VMs. Truth be told, the current position of Containers make them not suitable replacements for all VMs just yet. When choosing between Containers and VMs, there are several key factors that must be considered. One of the most important reasons is the issue of the application’s environment. The aforementioned immutable functionality of containers, though beneficial to the operations of the application, means that the system environment is not a freely modifiable. As a result, if managers need to upgrade or change system configurations, they will encounter a lot of trouble. This usually requires the developer themselves to step in, and rewrite any parts of the program that may be an issue. Conversely, it would be relatively easy for an operator using a VM to manage the system environment.

Simply put, if a cloud service meets any of the following two conditions, a VM’s architecture would be more suitable for your needs.

  1. Managers would need to manage the base systems of the application’s environment
  2. The application needs to be built on many different operating systems

Otherwise, in most cases it is recommended to containerize the application to keep up with the current trends and market competitiveness.

Written By 陳逸凡 迎棧科技解決方案架構師

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