Key components of a virtual machine in KVM

In KVM (Kernel-based Virtual Machine), a virtual machine is composed of several elements that interact to emulate a complete hardware environment. Understanding each component helps you manage, troubleshoot, and optimize your VMs more efficiently. 1. Main components Component Description Virtual CPU (vCPU) Cores assigned from the physical host to the guest. Defined with --vcpus when creating the VM. Memory (RAM) Amount of memory assigned. Configured with --ram or can be hot-adjusted with virsh setmem. Virtual disk Storage file (.qcow2, .raw, etc.) used as the guest disk. Managed with virsh vol-* or virt-manager. Network interface Virtual connection (usually virtio or e1000) attached to a libvirt network (default, br0, etc.). Graphics device / console VNC, SPICE, or text mode (no graphical console). Controllable with --graphics or virsh vncdisplay. Firmware / BIOS / UEFI Defines the boot mode (traditional BIOS or UEFI with OVMF). Additional devices CD-ROM, USB controllers, serial channels, sound interfaces, etc. 2. Essential commands to retrieve VM information Once the VM is created, you can use virsh to inspect and manage all its details.