Virtualisation and Containerisation

Hardware

Determine CPU virtualisation support

lscpu | grep Virtualization
egrep "svm|vmx" /proc/cpuinfo

• AMD: AMD-V
• Intel: VT-x

Paravirtualisation (VirtIO): provides more direct access to host’s memory, storage, GPU and other devices for improved performance. Guest is aware of virtualisation.

Hypervisors

Type 1: runs directly on computer’s underlying hardware

• KVM
• vsphere
• hyper-v
• Proxmox
• XCP-ng and Xen
• Nutanix AHV

Type 2: runs on top of underlying OS

• VirtualBox
• VMWare Fusion, Workstation
• bhyve
• qemu: emulate hardware, can utilise KVM

Containerisation

• protected spaces, self-contained
• share host’s kernel
• portable and flexible
• created from file system images
• optimized to run a service/application without additional software

Container applications

• Docker
• LXC

Virtualisation

• KVM
• QEMU

Orchestration

• public/tech/dev/Vagrant
• libvirt
• Kubernetes
• Podman

Operation

• display
  • VNC (virtual network connection): easy, but not very fast or secure way to connect to display

Storage

Disk Image Files

Formats

• raw
• QCOW2 (QEMU copy-on-write): snapshots, sparse files

Overlay

Common scenario: use immutable read-only disk image with multiple guests and individual overlayed images to save space.

• over extended period of time, updates and other changes can lead to great deviation between overlay and backing image

References

• OCI: Open Container Initative: open governance structure for the express purpose of creating open industry standards around container formats and runtimes

Images

• OpenStack image guide