VPS's three virtual technologies OpenVZ, Xen, KVM comparison

Many people see the same configuration of VPS prices vary greatly, do not understand, in fact, VPS uses a variety of virtual technologies, such as OpenVZ, Xen, KVM , Xen and HVM and PV. In +XEN pv is semi-virtualized, hvm is fully virtualized, pv can only be used in linux kernel system, more efficient, hvm can virtualize all common operating systems (can use windows), + theoretical efficiency is slightly lower than pv In addition, hvm requires cpu virtualization instruction support, pv does not have this requirement. KVM is an emerging virtualization project. There are not many VPS vendors selling KVM, but KVM virtual technology + is said to be more powerful. OpenVZ is an operating system-level full virtualization solution similar to Linux-VServer. Currently, VPS service providers based on Xen and OpenVZ are more than +. This article makes a brief introduction and comparison of several common technologies used by VPS, OpenVZ, Xen, and KVM, in order to prepare your own suitable VPS.

OpenVZ

OpenVZ is an operating system level virtualization technology that is a layer of application on the underlying operating system, which means easy to understand and low weight overhead, which in general means more Excellent performance. However, OpenVZ is more flexible to configure, giving black-hearted service providers the opportunity to change their limits.

Advantages: This type of selling outside, the licensed memory is too large, the CPU is also strong, and the seller is many, the comparability is also very strong. High cost performance.

Disadvantages: Oversold, no oversold, resulting in a variety of stone plates, diamond plates. The associated cpu is also over-segmented, resulting in a performance appreciation that is less than 1/10 of its rating. Then there is memory. Basically, OpenVZ technology is not exclusive. It is shared. If you have more people, you will have less, and the biggest disadvantage of this technology is that it is directly down when the memory is down. There are also various inconveniences in opening vpn.

Xen

Xen is a paravirtualization technology. It is not a real virtual machine. It is equivalent to running a kernel instance. You can freely load kernel modules, virtual. Memory and IO, stable and predictable. The difference between Xen+pv+ and Xen+hvm is that pv only supports linux, while hvm supports win system.

Advantages: Memory is exclusive, although small but guaranteed to be distributed. Part of the virtual technology determines that even if it is oversold, it will not be too outrageous. Therefore, even if the average hen is over, it will rarely lead to a stone plate. Of course, the chicken has pt except it. The other is that even if the memory is low, it will not be destroyed, but it will not respond for a while.

Disadvantages: small memory, small hard disk, small bandwidth (the above 3 points are compared with the same price openvz). Because it can't be oversold, in order to make money, only these three basic configurations can be reduced. There is also a shortage of suppliers, and most of them say that xen is a pv or hvm, in fact, pv performance is better than hvm.

KVM

Advantages: Similar to xen, a better point than xen is that kvm is completely virtual, so regardless of the difference between pv and hvm, all kvm class + type virtual Technology can be installed with a variety of linux distributions and various win distributions, regardless of whether the vendor has written on the home page whether it supports win, as long as you configure enough win to run, then you can definitely install + up, just the method The problem is nothing more.

Disadvantages: precisely because kvm can be installed with any type of operating system, resulting in the tossing emperor even installed on the 128m machine win2003 (up to + directly after all the cpu and memory are used for hard disk IO, do not understand These people want to do God.) The result is that all kvm neighbors have to look at the faces of neighbors around you. So to say, as long as a node has 5 or 6 such tossing emperor, sorry, your hard disk is basically a stone disk.

Personally prefer Xen because it is an acceptable compromise for both suppliers and customers. Openvz oversold too much, kvm and so on to see RP, these two are not suitable for those who do not want to toss only want to do the station.