Difference Between Containers and Virtual Machines
One of the frequent questions asked about Docker is how the container different from VM (virtual machine).
Containers and VMs each have their own use cases, many deployments of containers use VMs as the host operating system rather than running directly on the hardware, which provides one more additional layer of high availability in the form of Virtual Machine.
Let’s see then how and what makes the container different than virtual machines.
Image Source from Redhat
If you observe the above reference diagram, the Hypervisor layer is Enabling/Supporting to create a virtual machine, and in the same fashion, Runtime is allowing to run containers on top of the Operating system.
The below table shows the list of major differences w.r.t feature associated with it:
| Feature | Virtual machine | Container |
| Isolation | Hardware-level process isolation | OS level process isolation |
| Operating system | Each VM has a separate OS | Each container can share OS |
| Boot-Time | Boots in minutes | Boots in seconds |
| Guest compatibility | Runs just about any operating system inside the virtual machine | Runs on the same operating system version as the host (Linux Containers run on Linux Host os & Windows Containers run on windows Host OS |
| Size | VMs are of few GBs | Containers are lightweight (KBs/MBs) |
| Persistent storage | We can use additional disk for local storage or Cluster File System (Like NFS) for storage shared by multiple servers | We can use additional disk for local storage or Cluster File System (Like NFS) for storage shared by multiple servers |
| Fault tolerance | VMs can failover to another server in a cluster, with the VM’s operating system restarting on the new server. | If a cluster node fails, any containers running on it are rapidly recreated by the orchestrator on another cluster node. |
| High Availability | VMs can move to new host easily | Containers are destroyed and re-created rather than moving |
| Deployment Time | Creating VM takes a relatively longer time | Containers can be created in seconds |
| Resource Allocation/Consumption | More resource usage | Less resource usage |
Final Thoughts.
Virtual machines and containers contrast in a few different ways, however, the key difference is that containers give an approach to virtualize an OS so that multiple workloads can run on a single OS. With VMs, the hardware is being virtualized to run multiple OS instances. Containers’ speed, agility, and portability make them yet another tool to help streamline software development.
Below workloads can run on containers:
- Cloud-native applications like web servers.
- Distributed applications
Below workloads can run on the virtual machine:
- Heavy Transactional Databases
- Any application which requires tight binding with OS like Informatica.
At the end of the day, every organization’s business needs and infrastructure are different and requires its own unique strategy. So, as try to be you.