Both types of virtualization have distinct advantages and disadvantages. Choose which one is suitable for you.

OpenVZ is an operating system-level server technology that’s actually based on the Linux kernel and OS. You can only run linux operations systems in an OpenVZ VPS, and you cannot make any kernel level modifications inside the VPS. The VPS’s on the host rely on the hosts kernel. One advantage of this is that it doesn’t have the overhead a true hypervisor does.

KVM is true virtualization where the VPS operates as its own server, independently of the host node. Almost any operating system can run on three platforms: Linux, BSD or Windows.  Since KVM is true virtualization, reliability and uptime on average should be greater under KVM.


Comparations between OpenVZ vs KVM

Disk Resize

KVM can only increase in size
Rebootless Upgrades

Changes to kernel, disk, or memory do not require reboots
Lowest Overhead
The shared kernel on openvz has lower overhead
Support ALL OSNoYes
Full Disk EncryptionNoYes
Disk CacheYesYes
Swap SpaceNoYes