Quiz: Virtualization

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3 questions

L0 (1 questions)

1. What are the three components of the standard Linux virtualization stack, and what does each do?

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KVM provides hardware-accelerated CPU and memory virtualization via a kernel module. QEMU emulates devices (disk, network, USB) in userspace. libvirt provides a unified management API so tools like virsh and virt-manager don't need to know QEMU internals.

L1 (1 questions)

1. Why should you always use VirtIO devices instead of emulated legacy devices (e.g., e1000 NIC) in production VMs?

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VirtIO is a paravirtualized framework where the guest OS cooperates with the hypervisor, reducing overhead. Emulated legacy devices (e1000, IDE) carry significant CPU overhead because the guest doesn't know it's virtual. VirtIO-net is 2-10x faster than e1000, and virtio-blk is 2-5x faster than emulated IDE/SATA.

L2 (1 questions)

1. A VM on a dual-socket server has high memory access latency despite having enough RAM. What is the likely cause and how do you fix it?

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The VM's vCPUs and memory are likely split across NUMA nodes, causing cross-node memory access with 40-100ns additional latency per access. Fix by pinning the VM to a single NUMA node: 'virsh numatune web01 --mode strict --nodeset 0' and pin vCPUs to cores on the same node with 'virsh vcpupin'.