[James Pepper]

Virtualisation and containers are both technologies that provide isolated environments for running applications, but they do so in different ways and serve different purposes.

Virtualisation involves running multiple virtual machines (VMs) on a single physical host, each with its own operating system (OS). This provides complete isolation from the host OS and other VMs, which is useful when a strong security boundary is critical. VMs run a complete OS including the kernel, thus requiring more system resources (CPU, memory, and storage). VMs can run just about any OS inside the virtual machine.

Containers, on the other hand, are isolated, lightweight silos for running an application on the host OS. They build on top of the host OS’s kernel and contain only apps and some lightweight OS APIs and services that run-in user mode. Containers typically provide lightweight isolation from the host and other containers, but do not provide as strong a security boundary as a VM. They run the user mode portion of an OS and can be tailored to contain just the needed services for your app, using fewer system resources. Containers run on the same OS version as the host.

Many deployments of containers use VMs as the host OS rather than running directly on the hardware, especially when running containers in the cloud. This shows how virtualisation and container technologies often complement each other, leading to better performance, resilience, and flexibility.

To optimise resource utilisation when balancing these technologies, organisations can consider the following strategies:

1. Implement Resource Limits and Quotas: Set resource limits for CPU, memory, and I/O usage to prevent a single container or VM from monopolising resources.
2. Right-sizing Containers and VMs: Analyse your application’s resource demands and configure container and VM sizes accordingly.
3. Use Container Orchestration Tools: Tools like Kubernetes and Docker Swarm provide features to manage and optimise container resource utilisation.
4. Optimise Docker Images: Use official base images, minimise the number of layers, and use .dockerignore to exclude unnecessary files.
5. Monitor Resource Usage: Use monitoring tools such as Prometheus and Grafana to identify resource usage patterns and make informed decisions about container and VM sizes.

Remember, the choice between virtualisation and containers, and the balance between them, depends on your specific use case and requirements.

[Lucas Thompson]

cheers for the information didn’t really think about VMs hosting containers.