KVM vs. OpenVZ: Which Virtualization Technology to Choose?

What is KVM Virtualization?

Kernel-based Virtual Machine (KVM) is an open source software which allows you to turn a linux server into a hypervisor. This enables the server to be split into multiple VIrtual Machines (VMs), which each have their own isolated Operating System environment and dedicated resources. Every VM is treated as a regular Linux process, scheduled by the Linux scheduler, with dedicated virtual hardware like a network card, graphics adapter, CPU(s), memory, and disks.

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KVM Key Features

QMP – Qemu Monitor Protocol

A JSON-based protocol that allows applications to communicate with a QEMU instance. The qemu-monitor-command provided by the virsh shell allows users to interact with the QEMU monitor from the command line.

KSM – Kernel Samepage Merging

A kernel feature that makes it possible for a hypervisor system to share identical memory pages amongst different processes or virtualized guests.

KVM Paravirtual Clock

A paravirtual timesource for KVM.

CPU / PCI Hotplug support

Adding CPU’s and PCI cards on the fly.

Vmchannel

Communication channel between the host and guests

Migration

Move virtual machines between nodes.

Nested Guest

Running virtual machines within virtual machines.

How much does KVM cost?

KVM is an open-source software and as such, it is completely free to use. Unlike VMware and Hyper-V, there are no additional licensing costs associated with KVM.

KVM Hardware Requirements

In order to run KVM, the hardware must be x86 and have hardware virtualization support for Intel VT or AMD-V.

The CPU, memory, and network requirements will vary depending on how many VMs you wish to run on the hypervisor and what resources will be allocated to each VM. The hypervisor will need additional overhead resources in order to manage the VMs outside of the resources allocated to the VMs.

Recommended KVM Servers

KVM Downloads

The KVM software can be downloaded on the KVM Project Website.

What is OpenVZ Virtualization?

OpenVZ is an open source linux virtualization platform. Similar to KVM, it allows a linux server to be partitioned into isolated Virtual Private Servers (VPSes). OpenVZ uses a single Linux kernel and therefore VPSes on OpenVZ can only run Linux.

OpenVZ Key Features

• Two-Level Disk Quota
• Fair CPU Scheduler
• I/O Scheduler
• User Beancounters
• Checkpointing and live migration

How much does OpenVZ cost?

OpenVZ is completely open source and has no licensing fees or other costs associated with using the software.

OpenVZ Hardware Requirements

In order to run OpenVZ, the hardware must have hardware virtualization support for Intel VT or AMD-V. We recommend at least 4 CPU cores and 8GB of memory with 32GB of SSD powered disk space. These hardware requirements will vary based on the number of VPSes you wish to run on the node and how much resources each VPS will require.

Recommended OpenVZ Servers

OpenVZ Downloads

OpenVZ can be downloaded on the OpenVZ website.

Comparing OpenVZ vs. KVM

OS Support

OpenVZ uses a single Linux kernel and therefore can run only Linux, meanwhile KVM VMs can run both Linux and Windows Operating Systems.

Kernel Versions

OpenVZ containers share the same architecture and kernel version while KVM VMs can each run a different kernel version than the hypervisor. The advantage of sharing the same kernel is that OpenVZ has a lower overhead on the hypervisor.

Memory Distribution

Using OpenVZ, memory that is not used by one container can be used by other containers. KVM on the other hand has a hard memory limit, which can lead to more stable resource distribution.

In Summary

Are you looking to deploy a server and use virtualization to divide the server? Our server experts have years of experience choosing the right server for your next project. Book a server consultation and we’ll help you choose the right server for your needs and budget.