Virtualization Technology Comparison PV HVM

Many people see the same configuration vps price difference is very large, very do not understand, in fact VPS Use virtual There are many kinds of technology, such as openvz, xen, KVM, xen and HVM with PV. In Xen PV is semi-virtualized, HVM is full virtualization, PV can only be used for Linux kernel systems, more efficient, HVM can be virtual all Common operating systems ( can use Windows), theoretical efficiency is slightly lower than PV, in addition, HVM requires CPU virtualization instruction support (CPU must turn on Intel VT or AMD-V), PV does not have this requirement. The KVM is a new virtualization project that sells KVM vps not many merchants, but it is said that the KVM virtual technology is more powerful. and openvz is a linux-vserver-like operation system-wide virtualization solution, currently based on xen and OpenVZ are more than VPS service providers. This article introduces and contrasts several common techniques openvz, Xen, and KVM used by VPS in case you choose your own VPS.

Openvz

OpenVZ is an operating system-level virtualization technology that is a layer of application on the underlying operating system, meaning ease of understanding and low weight overhead, which generally means better performance. But OPENVZ configuration is more flexible, to the black-hearted service providers to reduce the opportunity to limit.

Advantages : Now outside the type of sale, the permitted memory is very large, the CPU is also strong, and sellers a lot, comparable is also very strong. Very good value for money.

disadvantage : Oversold, no not oversold, resulting in a variety of stone plate, diamond plate. The associated CPU is also over-segmented, resulting in a performance appreciation less than 1/10 of its mark. Then there is the memory, basically OPENVZ technology is not exclusive, are shared, others more you are less, and this technology is the biggest disadvantage is the memory is directly after the machine. There are also various inconvenient to open a VPN.

Xen

Xen is a semi-virtualized technology, it is not a real virtual machine, but the equivalent of 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, and HVM supports the win system.

Advantage : Memory exclusive, although small but guaranteed to be assigned. Part of the virtual technology determines that even oversold is not too outrageous. So the average hen even super, also rarely lead to stone plate. Of course, the chickens have pt, except. The other thing is that even if the memory is low, it will not be dropped, but it won't respond for a while. More difficult to sell!

disadvantage : Small memory, hard disk, small bandwidth (above 3 points and the same price of OpenVZ contrast). Because did not sell oversold, in order to make money can only put these 3 basic configuration lowered. There is supplier error, and most of the time is said Xen Mi Youming is PV or HVM, in fact, PV performance is better than HVM.

Kvm

Advantage : Similar to Xen, a better thing than Xen is that KVM is completely virtual, so no difference between PV and HVM, all KVM-type virtual technology can be loaded with various Linux distributions and various win distributions, Whether or not the supplier on the homepage has indicated whether to support win, as long as you configure enough win to run, it will certainly be installed up, just the problem of the method.

disadvantage : Just because KVM can be installed any type of operating system, resulting in the toss of the emperor even in the 128m machine installed win2003 (up directly after all the CPU and memory are used for hard disk IO, do not understand these people want to do God horse). The result is that all KVM neighbors have to look at the faces of your neighbors. So say, a node under as long as there are 5, 6 This toss Emperor, sorry, your hard disk is basically a stone plate.

Individuals tend to be more inclined to Xen because it is an acceptable compromise for both suppliers and customers. OpenVZ oversold too much, KVM and so look at RP, these 2 kinds are not suitable for those who do not want to toss only want to do station webmaster.

Http://docs.aws.amazon.com/zh_cn/AWSEC2/latest/UserGuide/virtualization_types.html

Amazon system images Use one of two types of virtualization: Semi-virtualized (PV) or hardware virtual machines (HVM). Some current generation instance types support only hardware virtual machine amis, while some previous generation instance types only support semi-virtualized AMIS. The main difference between semi-virtualized and hardware virtual machine Amis is how they are started and whether they can take advantage of special hardware extensions (CPU, network, and storage) for better performance. For best performance, we recommend that you use the current generation instance type and hardware virtual machine AMI when launching a new instance.

Paravirtual (PV)

Para-virtualization can run on host hardware that does not have explicit virtualization support, but cannot take advantage of special hardware extensions, such as enhanced networking or GPU processing. In the past, the performance of semi-virtualized in many cases was better than that of hardware virtual machines, but the situation changed because of the enhanced functionality of hardware virtual machine virtualization and the use of semi-virtualized drivers for hardware virtual machine AMIS.

Hardware Virtual Machine (HVM)

The hardware virtual machine AMI is equipped with a set of fully virtualized hardware that is launched by executing the master boot record of the image root block device. Both Linux and Windows AMIS can use hardware virtual machine virtualization. This type of virtualization allows you to run the operating system directly on a virtual machine without making any modifications (as if it were running on bare metal hardware). The Amazon EC2 host system simulates some or all of the underlying hardware that is provided to the virtual machine.

Unlike para-virtualization, hardware virtual machines can take advantage of hardware extensions that provide fast access to the underlying hardware on the host system.

Semi-virtualized on a hardware virtual machine

In the past, semi-virtualized performance was better than hardware virtual machines in terms of storage and network operations, because they could use special drivers for I/O to avoid the overhead of simulating network and disk hardware, and hardware virtual machines had to convert these instructions into emulated hardware. These semi-virtualized drivers are now available for hardware virtual machines, so operating systems that are running in a semi-virtualized environment, such as Windows, can still use them to gain performance benefits in storage and network I/O. With the semi-virtualization on these hardware virtual machine drivers, hardware virtual machines can achieve the same or even better performance than semi-virtualized guests.

http://blog.csdn.net/blade2001/article/details/16864473

Virtualization Technology Comparison PV HVM