There are many virtual technologies of VPS (Virtual Private Server). VPS divides a server into multiple virtual servers through some kind of virtual technology. The commonly used virtualization technologies for VPS are OpenVZ , Xen, and KVM . Different virtual machines with the same configuration of VPS may have very different prices. So what are these three virtualization technologies, and what are the differences between them? This article gives a brief introduction to the three virtualization technologies of OpenVZ, Xen, and KVM, and compares the differences between them, hoping to help you choose VPS in the future.
OpenVZ Virtual Technology
Introduction to OpenVZ: OpenVZ is an operating system-level virtualization technology, that is, it runs on Linux, and runs a layer of applications on the underlying operating system, and installs a server into multiple operating system instances through virtualization technology, so that each instance It is a VPS, which means easy-to-understand and low-weight overhead, and applications can run directly on the CPU without having to approach virtual instructions, so generally OpenVZ will have better performance, and compared to the other two common virtual technologies, Inexpensive.
Advantages of OpenVZ:
- The price of OpenVZ is low, higher configuration can be bought at the same price, and the memory and CPU are generally better.
- Sharing a core, high efficiency and better performance.
Disadvantages of OpenVZ:
- OpenVZ can only install Linux, not Windows.
- The core core is shared, and each VPS instance cannot modify the core independently (so bbr cannot be turned on according to normal operations).
- Oversold! ! ! ! There is basically no OpvenVZ that is not oversold. Because the CPU and memory of the same host machine are shared, the overselling phenomenon will seriously reduce the speed, and the CPU and memory are often not as good as guaranteed by the VPS service provider.
Xen Virtual Technology
Introduction to Xen: Xen is a para-virtualization technology. It is not a real virtual machine, but an instance of running a kernel by itself, and can freely load kernel modules, virtual memory and IO. Xen virtualization technology can be divided into two types, Xen PV and Xen HVM. Among them, Xen PV only supports Linux system, while Xen HVM supports WIndows system, and the performance of the former is higher than that of the latter.
Advantages of Xen:
- Exclusive memory, although small, is guaranteed to be allocated.
- Paravirtualization ensures that the oversold phenomenon will not be severe compared to OpenVZ, and the impact of overselling on performance is not as great as that of OpenVZ.
Disadvantages of Xen:
- At the same price, compared with OpenVZ, the memory is smaller, and the CPU and IO performance are worse.
KVM virtualization technology
Introduction to KVM: KVM is completely virtual, and each VPS instance does not share the kernel of the host machine, and each is independent of each other. And as long as your configuration is sufficient, KVM theoretically supports any version on Linux and Windows.
Advantages of KVM:
- Fully virtualized, you can install Linux or Winodws.
- Independent kernel, memory, CPU, perfect support for TCP BBR acceleration.
Disadvantages of KVM:
- Because KVM supports any operating system, if too many windows are installed on the same node, it may affect the use of extremely hard disks.
Comparison among the three virtualization technologies of OpenVZ, Xen and KVM
In summary,
- OpenVZ is the most cost-effective virtualization technology without overselling: low price and good performance. but! ! ! There is basically no VPS service provider that does not oversell OpenVZ, so the machines you often get are much smaller than the ones described.
- To be honest, I haven't used Xen virtualization technology, but it has two types: PV and HVM. The support for the system is separated, and the stability is relatively better.
- KVM is a virtualization technology I recommend. It has exclusive use of the kernel and memory. Compared with OpenVZ, it has better stability and is less affected by overselling. To install Winodws, and it perfectly supports BBR acceleration, make a ss server beautiful .