6 facts that will clear up any confusion about containers and virtual machines

 In Cloud, Virtualization

If we created a list of top IT trends of 2016, what would be at the top? Big data tools replacing your doctor? Machine learning and AI’s new levels of sophistication? The rise of adaptive security architectures?

How about the growing popularity of containers? Over the past few years, this old technology has become a beloved tool for software engineers shirking monolithic development. Containers are small and fast, and enable rapid development and improved productivity without consuming many resources.


Many IT professionals have questions about containers because they’re often compared with virtual machines (VMs). These two technologies solve different problems, but in similar ways. IT is left asking: Will containers replace VMs? Are they secure? Do containers and VMs do the same thing? Can my IT environment handle both?

Let’s cut through the confusion. Here are six facts you need to know about containers and VMs.

1. A container is an operating system virtualized. Containers divide one operating system into smaller environments, and multiple containers can run on a single OS. Each container shares the host OS kernel and typically shares the binaries and libraries as well. The container host requires a containerization engine like Docker, and it leverages the process and file isolation features of the Linux kernel.  Because they share the host operating system, containers are very lightweight, but they can be megabytes in size and start in just seconds.

Containers are different from VMs, which virtualize hardware so multiple operating system instances can run on the same physical server. Each VM has a unique operating system that needs to be managed and patched separately, as well as its own binaries, libraries, and applications. VMs can be gigabytes or larger in size while consuming additional CPU and RAM.

2. Software developers love containers. Portability is a key advantage of containers, as developers can easily move a container from a laptop to a test environment and then to production. Because containers are fast, portable, and easy to deploy, they’re increasingly used in DevOps organizations that prioritize continuous software delivery.

Containers give developers a way to write code that is flexible, small, and sharable. This ties into the microservices approach where code is deployed into modular components that are reused and shared. Because containers can be easily shipped from one environment to another, they give development teams the ability to develop and innovate quickly.

3. If an organization wants to be cloud agnostic, containers can help. Containers are based on open standards, so they can run on all major Linux distributions, Microsoft Windows, and on top of any cloud infrastructure.

In comparison, VM architectures lock an organization into a specific format. Virtual machines built with one vendor’s technology cannot run natively on other hypervisors, and they require a conversion process for each different cloud provider. For this reason, many organizations are re-architecting their applications to run in containers.

4. VMs and containers have different roles, but play well together. VMs primarily run  traditional, on-premises applications. They’re also battle tested and secure, which is why virtual machines are so widely adopted.

But containers are rapidly gaining popularity for cloud application development. Many organizations are experimenting with containers to streamline internal processes, improve resource efficiencies, and prepare for a move to the cloud. By breaking an application into microservices, new features can be brought to market faster and with less code debugging.  Containers can also be easily deployed on top of VMs.

5. Containers are built for speed and portability, and VMs are built for availability. Containers are speedy and lightweight, and more can be packed onto a server than traditional VMs. Their portability means developers can quickly share containers to streamline jobs and processes.

VMs are scalable and high performing, and they’re the right technology for running multiple applications on multiple servers. They’re more established, offering higher availability, security, and isolation than containers, though VMs are slower and consume more resources. In fact, it’s quite common for containers to run in virtualized environments to capitalize on the high availability and security features.

6. The container industry is responding to concerns. Containers aren’t new, but many in the enterprise space still have questions as container adoption increases. Security is a concern, as is data loss, performance, storage, and management. The major players in the container arena are listening and responded to security concerns by adding scanning tools that check for known vulnerabilities.

Containers replacing VMs? Unlikely.

Containers enable businesses to compete at a faster rate. They’re incredibly valuable to software developers because they’re so portable, and can speed up app development. The biggest cloud players – Amazon Web Services, Google, and Microsoft – have fine-tuned their offerings to meet expected demand as container integration grows.

But there’s been confusion about the role of containers and what VMs do. While VMs virtualize hardware, containers virtualize the OS. They often co-exist and join forces to complete different jobs. Containers are not a panacea, but another tool for cloud developers to be more efficient.

Containers allows for portability of applications, whereas VMs are designed to increase hardware utilization. Some organizations may choose to run containers directly on top of bare metal hardware as a replacement for VMs. However, VMs will be around for the foreseeable future.

What questions do you have about containers? About VMs? Leave us a comment below.

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  • Nic Caputo

    Great post. Iron.io is doing big things in the serverless multi-cloud space (item #3), great company to keep and eye on as organizations are architecting their container strategies.

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