Difference between KVM and LXC? Which suits my needs?


Full Time Hosting offers the Kernel-based Virtual Machine (KVM) and Container-based Virtualization/Linux Container (LXC) for the VPS and VDS packages. There is no ‘one best’ option because there are a lot of factors to consider and it really depends on individual needs and requirements. You can read more about KVM and LXC below:

Short Version

KVM is true virtualization where the VPS operates as its own server, independently of the host node. LXC is a container style of virtualization which relies on the host node’s kernel. KVM has no restrictions in terms of functionality, but it has more overhead than LXC. LXC is constrained by the host node kernel, but it has less overhead in the containers themselves. KVM is generally more stable than LXC.

KVM VPSs are not dedicated environments. Both virtualizations share host CPU and network port among all VPSs. Only our VDSs include dedicated CPU. You can read more about the difference between VPS and VDS here: What is the difference between VPS and VDS packages?

CPU Performance :heavy_check_mark:
Network Performance :heavy_check_mark: (with virtio)
Disk Performance :heavy_check_mark: (with virtio)
Can upgrade distribution version without reinstall :heavy_check_mark:
Can use Windows/BSD :heavy_check_mark:
Can change kernel :heavy_check_mark:
Can use application containers (Docker, etc.) :heavy_check_mark:

Long Version

Kernel-based Virtual Machine (KVM)

Create and manage Qemu/KVM Virtual Machines with Proxmox VE.

KVM is the industry-leading Linux virtualization technology for full-virtualization. It’s a kernel module merged into the mainline Linux kernel and it runs with near-native performance on all x86 hardware with virtualization support—either Intel VT-x or AMD-V.

With KVM you can run both, Windows and Linux, in virtual machines (VMs) where each VM has private virtualized hardware: a network card, disk, graphics adapter, etc. Running several applications in VMs on single hardware enables you to save power and reduce cost while at the same time gives you the flexibility to build an agile and scalable software-defined data centre that meets your business demands.

Container-based Virtualization

Create and manage lightweight containers with LXC.

Container-based virtualization technology is a lightweight alternative to full machine virtualization because it offers lower overhead.

Since containers are a lightweight alternative to fully virtualized VMs, instead of emulating a complete Operating System (OS), containers simply use the OS of the host they run on. This implies that all containers use the same kernel and that they can access resources from the host directly.

This is great because containers do not waste CPU power nor memory due to kernel emulation. Container run-time costs are close to zero and usually negligible. But there are also some drawbacks you need to consider:

  • You can only run Linux based OS inside containers, i.e. it is not possible to run FreeBSD or MS Windows inside.
  • For security reasons, access to host resources needs to be restricted. This is done with AppArmor, SecComp filters and other kernel features. Be prepared that some syscalls are not allowed inside containers.

Linux Containers (LXC)

LXC is an operating-system-level-virtualization environment for running multiple, isolated Linux systems on a single Linux control host. LXC works as a userspace interface for the Linux kernel containment features. Users can easily create and manage system or application containers with a powerful API and simple tools.

Which is better?

Well, they are both great because they cater to different types of customers with varied needs and requirements. But LXC is generally considered a bit faster (CPU performance). Network may be faster on LXC with low resources since it has no overhead. Moreover, you can’t install Windows on LXC and can’t use it as nested virtualization. But LXC is ideal for Linux based apps such as most of the game servers, VOIP servers like TeamSpeak, VPN servers etc.