Virtualization Uses and Containers

What it is

Virtualization is used for much more than running a second operating system. It gives a safe place to test, a way to keep old software alive, a way to run different systems on one computer and a way to deliver desktops from a central server.

This page lists the common purposes and compares virtual machines (VMs) with containers.

How it works

Sandbox

A sandbox is an isolated area where you can run untrusted software without risk to the main system. A VM is a good sandbox.

If the software is harmful, you delete the VM or return to a saved snapshot. Security staff use sandboxes to study suspicious files.

Test and development

Developers and technicians use VMs to try new software, updates, settings and scripts before using them on real systems. A test VM costs little, can be reset quickly and can be cloned many times. Test machines should be kept apart from the production network.

Legacy software and operating systems

Some old applications only run on old operating systems that no longer run on new hardware or get security updates. Running that system inside a VM keeps the application alive. Because the old system is exposed to risk, limit its network access and keep it isolated.

Cross platform virtualization

Cross platform virtualization runs one operating system on a computer that normally runs another, for example a Windows guest on a Mac or a Linux guest on Windows. It lets people reach apps that are not available on their main system.

An emulator mimics different hardware, such as a phone processor on a desktop computer. Emulation is slower than virtualization because it translates each instruction instead of using the real processor directly. Developers use emulators to test mobile apps.

Virtual desktop infrastructure

Virtual desktop infrastructure (VDI) runs users' desktops as virtual machines on central servers. Users connect from a thin client, a laptop or a phone and see the desktop on their screen.

Benefits include central management, easy updates and data that stays in the data centre. Drawbacks include the need for a good network connection and strong servers.

Application virtualization

Application virtualization runs a program in its own isolated environment without installing it fully on the user's computer. The app is delivered from a server or packaged, and it does not conflict with other software. It suits cases where an old version of an app must run beside a new one.

Containers

A container packages an application with the libraries and settings it needs, but shares the host's operating system kernel instead of carrying a full guest operating system. This makes containers small and quick to start.

Containers suit modern applications that must scale quickly. A VM suits cases that need a whole separate operating system or stronger isolation.

Requirements to plan for

Virtualization needs enough processor cores, memory, storage space and network speed for all guests. It also needs security: patched guests, an updated hypervisor, controlled network access and a plan to protect the virtual disk files, since copying a file copies a whole machine.