Container Vs VM: Which Is the Best Option for Your Organization?

Containers and virtual machines (VMs) are similar and complementary. Both enhance application portability, efficiency and augment Development and Operations (DevOps) in organizations, albeit with architectural differences. Containers create an abstraction layer at an OS level, allowing developers to focus on applications while the operations team focuses on the infrastructure.

VMs, in contrast, leverage a hypervisor to replicate the functionalities of the underlying hardware resources with application development. Choosing between a container versus a VM depends on the requirements of the deployed system.

How Containers and Virtual Machines Work

Container vs VMBoth containers and VMs are technologies that create self-contained, virtualized packages. Therefore, the simplest way to understand how they work is to start by defining virtualization. Virtualization allows you to isolate the OS from the underlying hardware. As such, you can run multiple OSes such as Linux and Windows on the same physical machine.

Traditional virtualization relies on a hypervisor to create virtual machines. The hypervisor isolates and orchestrates the available hardware resources such as processor, memory, storage and networking, assigning a portion to each VM on an as-needed basis.

Ultimately, each VM contains the guest OS, virtualized hardware that the guest OS needs to run, and installed applications, including associated dependencies and libraries.

Typically, a VM operates as an isolated PC, and the underlying infrastructure can run multiple, independent virtual machines for different workloads. Since each virtual machine requires its own guest OS, VM operations are resource-intensive. In most cases, you rarely find a workload operation consuming all the available resources within a VM.

You also cannot run an individual application functionality in a virtualized environment unless you use a separate VM for different software modular elements. Furthermore, to migrate an application between different VMs or datacenters, you have to move the entire OS along with it. It is this drawback that has popularized the adoption and use of containers.

Unlike VMs that use virtualized hardware, containers virtualize the OS, allowing individual, modular and distinct functionalities of the software to execute independently. Each container shares the read-only host OS’s kernel, including binaries and libraries.

Containers don’t require a guest OS in every instance they run—they simply use the host OS’s resources and features. Sharing OS resources allows the server to run multiple workloads on the same OS. Containers are thus light—they occupy a few megabytes—and are fast compared to VMs.

Like VMs, containers allow developers to enhance the processor, memory, and storage utilization of physical machines. However, containers even go further. They facilitate microservice architectures, where you can granularly deploy and scale application components efficiently.

How Containers and VMs Are Different

Containers and VMs differ in many ways, as summarized in the table below:

Feature Container Virtual Machine
Operating system It runs only the user-mode portion of the OS. You can customize containers by selecting only the services the application requires. It runs the entire OS, including the kernel. It is resource-intensive.
Isolation It does not isolate the host from other containers fully. As such, it does not offer a robust security boundary compared to a virtual machine. It offers complete isolation between the host OS and other VMs. As such, it provides robust security for organizations hosting applications on the same server or cluster.
Guest compatibility It runs on the same OS version as that of the host. It can run any OS that is inside the VM.
OS updates and upgrades You can update or upgrade a container’s OS files in two ways. First, you can edit and rebuild the image file. Secondly, you can use a containerization orchestrator. You can update or upgrade a VM’s OS by downloading and installing the updates on each virtual machine. This is tedious and time-consuming if you have many VMs.
Networking It uses an isolated view of the virtual network adapter (VNA). This offers light-weight virtualization where the host’s firewall is shared with other containers. It uses VNAs with complete virtualization.
Fault tolerance In case a cluster node fails, an orchestrator automatically recreates any container running on it to another node. A virtual machine fails over to another node in the cluster rapidly, with the guest OS restarting automatically.
Load balancing The orchestrator starts or stops containers on the cluster nodes automatically to handle changes in loads and availabilities. Containers do not move. VM load balancing moves the running virtual machines to other nodes in a failed over cluster.

How to Choose Between Containers and Virtual Machines

Both containers and VMs have pros and cons and therefore affect the decision you make. Ultimately, your choice depends largely on two things:

Containers are lightweight. You can quickly move them between different servers and across different cloud deployments, including private, public and hybrid environments. If your priority is to maximize the number of applications on a minimal number of servers, you can consider containers.

Containers are also ideal if you want to deploy cloud-native applications that leverage microservices architecture to achieve consistent development and deployment across private, public and hybrid cloud environments. The only caveat with containers is that they must be compatible with the underlying OS.

You can consider containers if you want to:

Implement cloud-native applications.

Virtual machines, in contrast, can run more operations than a single container. VMs are perfectly suited for monolithic workloads, which require all of the OS’s resources and functionality. However, the expanded functionality makes VMs less portable than containers. You can consider VMs if you want to:

When to Use Containers and Virtual Machines Together

You might be wondering why someone would want to use containers and VMs together. Well, containers share the host’s OS kernel, including binaries and libraries. Running Linux containers across different distributions is not an issue because most Linux distributions are built on top of the same kernel.

For example, you can run Ubuntu containers on CentOS-based hosts efficiently. However, the kernel sharing fact means that you cannot run Windows containers on Linux hosts and vice versa. To run these containers, you need to create a VM on the respective host. For example, you can create a Windows VM on a Linux host to run Windows containers. This is possible because a virtual machine utilizes its own OS, allowing the operating system to support the container engine.

Running a container inside a VM isolates it, limiting the scope of vulnerability attacks. For example, if 500 containers share an OS kernel on a bare-metal server and the operating system fails, all the 500 containers become compromised. On the other hand, if a VM hosting 50 or fewer containers becomes compromised, it affects only those containers. This failure cannot affect other VMs running different containers within the same server or cluster.

You can also integrate containers and VMs to achieve capacity optimization. Virtualization is popular in the enterprise IT arena because it facilitates server utilization. A single server can host multiple VMs, with each virtual machine hosting multiple container hosts. Besides, each server can host many traditional monolithic VMs. Integrating containers with traditional monolithic VMs allows IT administrators to maximize the utilization of the physical server.

Use Parallels RAS to Manage Your Virtualization Environment

Parallels® Remote Application Server (RAS) is an all-in-one virtualization solution that allows organizations to run and share virtual desktops and applications (hosted within VMs) from a central server. Organizations can containerize their applications and publish them using Parallels RAS for any user to access them on any device and platform, even remotely.

With built-in VM templates, Parallels RAS is simple to deploy, allowing IT administrators to automate the creation and deployment of virtual desktops and applications. Parallels RAS supports all the major hypervisors, including Hyper-V and VMware ESX. You can also use multiple hypervisors under the same Parallels RAS environment and manage resources from a single console.

Parallels RAS also makes it easy to build and manage any cloud infrastructure, including private, public, hybrid or multi-cloud. Most importantly, Parallels RAS provides foolproof virtualization services via numerous features such as data encryption, multi-factor authentication (MFA) and access-filtering policies.

Test drive your free, 30-day Parallels RAS evaluation, and experience its virtualization benefits for yourself!