Virtualization has come a long way since its early days, making it possible to break down a single physical server into multiple smaller virtual private servers (VPS).
Businesses and individual users alike are switching to virtualization to reap its numerous benefits, including reduced operating costs, minimized downtime, and increased agility and responsiveness. However, not everyone understands the difference between OpenVZ and KVM, two popular virtualization technologies.
OpenVZ Virtualization: Unbeatable Performance
First released in 2005 and currently developed by Virtuozzo and the OpenVZ community, OpenVZ (Open Virtuozzo) is an OS-level virtualization technology that allows a single physical server to run multiple isolated operating system instances, known as containers. Because OpenVZ doesn’t provide full emulation and doesn’t need to run multiple full OS kernels, it offers significantly better performance than competing virtualization technologies.
What makes OpenVZ special is the fact that it recognizes two types of resources: dedicated and burst. As the name suggests, dedicated resources are guaranteed to be available when needed. Burst resources, on the other hand, are not guaranteed to be available when needed because they are sourced from the server's unused capacity.
That’s why it’s so important to choose a reputable OpenVZ VPS provider like Bacloud. There are many OpenVZ VPS providers that bundle dedicated and burst resources together to make their product offerings seem more attractive than they really are.
The only major disadvantage of OpenVZ is the fact that it works only with Linux—no other host operating systems are supported. Those who would like to run multiple full OS kernels should instead use a hardware virtualization technology like KVM.
KVM Virtualization: Outstanding Flexibility
As we’ve already mentioned, KVM (Kernel-based Virtual Machine) is a true hardware virtualization solution that allows the Linux kernel to function as a hypervisor and simulate hardware for another OS to run on top of it, including Linux, Windows, BSD, Solaris, Plan 9, ReactOS, AROS Research Operating System, Haiku, and OS X.
Because KVM doesn’t make the distinction between dedicated and burst resources, it’s not possible for VPS providers to readily overcommit, provide more memory space than the physical server has available. End users benefit the most because they always get what they pay for. The only downside is that a significant performance penalty occurs whenever limits are reached.
Because each KVM guest has its own kernel, SELinux settings on the host have no effect on the guest's SELinux settings, and vice versa. The ability to fully customize SELinux settings makes KVM a very attractive choice for businesses that must comply with stringent security standards and regulations.
Perhaps the biggest disadvantage of KVM is that its performance doesn’t quite match that of OpenVZ, because KVM requires a running kernel inside the VPS, while OpenVZ runs a shared kernel, making it very lightweight.
Which Virtualization Should I Choose?
The differences between OpenVZ and KVM boil down to individual needs and preferences. Only KVM allows you to simulate hardware for another OS to run on top of it. OpenVZ is compatible only with Linux, making it unsuitable for those who are looking for a Windows VPS. Because OpenVZ has much lower overhead than KVM, it can deliver unmatched performance at a very affordable price, making it ideal for demanding workloads.