Virtualization has transformed network computing. First virtual machines, emulations of computer systems has gained popularity, while now the new trend is containerization. According to a recent study by 451 research, containers will grow annually by 40% through 2020.
In order to identify the best solution for your business, it is crucial to understand both of the virtualization techniques, how they compare to each other, and what are they best uses for each. In this article we are going to introduce your to the basics of these technologies and their uses.
Virtual Machines
Virtual machines or VMs can be described as software programs on top of a physical server, which emulate a specific hardware or computing system. This way seemingly separate computers can be run on hardware which is physically one computer. The operating system and their applications are sharing hardware resources from the host server or servers (also referred to as Host Machine). This is made possible by the underlying software called hypervisor. It imitates the hardware resources in a software environment, and lies between the hardware and the VMs (also called Guest Machines).
The resources of the virtualized hardware are pooled together, and made available to the apps according to their needs. The physical hardware can be scaled or changed without disrupting the app, and makes it possible to run several apps on one server. However, VMs are quite resource intensive as each machine requires it to run its own operating system, creating overhead in memory and storage footprint. This adds complexity from development to production, and limits portability between environments.
Containers
When using containers instead of virtualizing the whole computer, the operating system is already virtualized, and the applications are sitting on top of it. Containers share the same host OS kernel, and usually share the binaries and libraries. Shared components are read-only. This means that the server can run multiple workloads with a single OS, and Containers become lightweight, and take only seconds to run - while heavier VMs can take minutes to start. Compared to the VM, containers only need enough operating system, supporting libraries and system resources to run a program. This way 2-3 times as many applications can be programmed on a single server than on a VM. Sharing a common operating system means only one OS needs updates, bug fixes or patches.
Containers are especially useful when developing and deploying microservices and modern distributed applications (for more about microservices read here). Developers do not need to adjust their code according to the specific VM operating different app components. The complete app component can be executed entirely in its isolated environment, not affecting the rest of the apps. Containers tend to maximize resources within their own environment, proving to be more resource and cost effective. Containers are also infrastructure agnostic, meaning they are easy to move from servers to cloud infrastructure.
When to use VMs or Containers
Both containers and virtual machines have their pros and cons, and in the end their use is defined by the specific business needs. Some key differences are:
VMs are a better choice when running applications which require all of the operating system's resources and functionalities
VMs are also a better choice when managing several operating systems
Containers are a better choice when managing multiple applications through a minimal number of servers
Final thoughts
For many businesses, the ideal IT setup includes both VMs and containers. With the current state of the technology VMs have become highly flexible, while the minimum resource requirement of containers can provide maximum functionality.
However, for businesses which require agile and fast software development VMs have failed to deliver. For these companies, container speed, flexibility and portability help to streamline software development and deployment.