--- title: "LXC vs QEMU (KVM) on Proxmox: which one to use ยท NexoVirt" description: "LXC containers boot in a second and run Linux only; QEMU/KVM VMs run any OS with full isolation. Comparison table and when to use each." url: https://nexovirt.com/lxc-vs-qemu --- # LXC vs QEMU on Proxmox: container or virtual machine? LXC containers share the Proxmox host's Linux kernel: they boot in about a second, use almost no extra RAM and run Linux only. QEMU/KVM virtual machines bring their own kernel, so they run any OS, including Windows, with stronger isolation and live migration. Rule of thumb: LXC for Linux services, a VM for everything else. [See the comparison table](#comparison) [Manage both in one panel](https://nexovirt.com/proxmox-control-panel) ## What is the difference between LXC and QEMU? Both are guest types on the same Proxmox VE host. The difference is where the kernel lives. - ### LXC: a system container LXC is OS-level virtualization. Containers share the host's Linux kernel and run isolated user spaces on top of it. Nothing is emulated, so a container boots in about a second, uses almost no extra memory and packs densely onto a node. The trade-off: it runs Linux only and stays tied to the host kernel. - ### QEMU/KVM: a full virtual machine QEMU is a machine emulator; on Proxmox it runs with KVM, the kernel's hardware virtualization. Each guest is a complete computer with its own kernel and virtual hardware, so it runs Windows, BSD or a custom kernel, is strongly isolated and can live-migrate. The cost is a little more overhead than a container. ## LXC vs QEMU at a glance Same Proxmox host, two different trade-offs. | Aspect | LXC (container) | QEMU/KVM (virtual machine) | |---|---|---| | Virtualization type | OS-level, shares the host kernel | Full hardware virtualization (KVM) | | Guest operating systems | Linux only | Any OS: Linux, Windows, BSD | | Overhead and density | Very low, many per node | Higher, a full VM per guest | | Boot time | About 1 second | A full OS boot | | Isolation | Shared kernel (namespaces, cgroups) | Strong, separate kernel | | Own kernel and modules | No, uses the host kernel | Yes | | Migration between nodes | Restart migration (short downtime) | Live migration | | Snapshots | Filesystem snapshots (storage-dependent) | Disk plus optional RAM state (vmstate) | | Typical use | Dense Linux services, web apps, dev boxes | Windows, mixed OS, untrusted or strict-isolation guests | ## When should you use LXC or QEMU? Start with the guest OS and how much you trust the workload. Everything else follows. ### Choose LXC when - The workload is Linux and you want as many guests per node as possible. - You want boots in about a second and almost no memory overhead. - It is a web app, database, reverse proxy, DNS server or dev box. - Sharing the host kernel is fine (no custom kernel modules). ### Choose QEMU/KVM when - You need Windows, BSD or any other non-Linux OS. - You need your own kernel, kernel modules or a specific kernel version. - The guest is untrusted or belongs to a customer: isolation matters. - You want live migration between nodes without downtime. Running Docker? An unprivileged LXC with nesting and keyctl works for a homelab; for production or untrusted images a small VM is the safer default. The steps are in [Docker in an unprivileged Proxmox LXC](https://nexovirt.com/blog/docker-in-unprivileged-proxmox-lxc). - ## Does Proxmox use QEMU or KVM? Both. KVM is the Linux kernel module that lets the CPU run virtual machines at near-native speed. QEMU is the program that provides the virtual hardware (disks, network cards, display). Proxmox VE runs every virtual machine with QEMU accelerated by KVM, which is why "QEMU", "KVM" and "QEMU/KVM" all name the same guest type. So "LXC vs KVM" is the same question as "LXC vs QEMU". - ## Privileged or unprivileged LXC? Use unprivileged containers. They map container root to an unprivileged user ID on the host, so root inside the container is a normal user outside it. A privileged container runs its root as real host root: less isolated and only for fully trusted workloads that need host-level access. Docker in LXC also stays unprivileged and gets the nesting and keyctl features instead. ## Run LXC and QEMU side by side Most Proxmox setups end up with both. NexoVirt manages containers and VMs on all your hosts in one panel, without logging into each node. - ### One list for every guest LXC and QEMU guests from all hosts in one searchable list with live status, IP, cores, RAM and storage. - ### One create wizard Containers from CT templates, VMs from cloud-init images, with the same plans, IP assignment and SSH keys. - ### Console, snapshots, firewall In-browser console, snapshots and a per-guest firewall for both types, in the panel and the REST API. [See the Proxmox control panel](https://nexovirt.com/proxmox-control-panel) [Sell VPS on Proxmox](https://nexovirt.com/proxmox-vps-panel) ## LXC vs QEMU FAQ What is the difference between LXC and QEMU?LXC is OS-level virtualization: containers share the host Linux kernel, so they are lightweight, boot in about a second and pack densely, but run Linux only. QEMU (with KVM on Proxmox) is full hardware virtualization: each guest is a complete virtual machine with its own kernel, so it can run any OS and is strongly isolated, at the cost of a little more overhead. Is LXC faster than QEMU?For Linux workloads, LXC generally has lower overhead and much faster boot times because there is no hardware to emulate and no second kernel to run. QEMU/KVM adds a small amount of overhead in exchange for full isolation and the ability to run any operating system. For most CPU-bound Linux services the day-to-day performance difference is small. Is QEMU the same as KVM?No, they work together. KVM is the Linux kernel module that provides hardware-accelerated virtualization; QEMU is the user-space emulator that provides the virtual hardware. On Proxmox, QEMU uses KVM, so "QEMU", "KVM" and "QEMU/KVM" all refer to the same full-VM guest type. "LXC vs KVM" is the same question as "LXC vs QEMU". When should I use LXC instead of a VM?Use an LXC container when the workload is Linux and you want maximum density, fast boots and minimal memory overhead, for example web apps, databases, reverse proxies or dev boxes, and you do not need a custom kernel. Use a QEMU/KVM VM when you need Windows or another non-Linux OS, a specific kernel, strong isolation for untrusted guests, or live migration. What is the difference between privileged and unprivileged LXC?An unprivileged container maps its root user to an unprivileged host UID, so container root is a harmless normal user on the host. It is the safe default. A privileged container runs its root as real host root, which is less isolated and should be reserved for trusted workloads that need host-level access. Can Proxmox run both LXC and QEMU?Yes. Proxmox VE runs LXC containers and QEMU/KVM virtual machines on the same host, and you can mix them freely. NexoVirt manages both guest types together in one panel and one REST API, with a shared create wizard, console, snapshots and per-guest firewall. ## Keep reading - [ Docker in a Proxmox LXC The pct set command for nesting and keyctl, and the common errors. ](https://nexovirt.com/blog/docker-in-unprivileged-proxmox-lxc) - [ Proxmox snapshots Rollback points for containers and VMs, and how they differ from backups. ](https://nexovirt.com/proxmox-snapshots) - [ Cloud-init on Proxmox Turn a cloud image into a configured VM on first boot. ](https://nexovirt.com/blog/cloud-init-on-proxmox) ## Start running NexoVirt today Free for homelabs with unlimited VMs on up to 2 nodes. Running a hosting business? Upgrade in place when you grow, no migration. [Install free](https://docs.nexovirt.com/getting-started/installation/) [See pricing](https://nexovirt.com/pricing)