What are the three commonly used virtualization technologies?

There are currently three common virtualization technologies: 1. OpenVZ, an operating system-level virtualization technology that is more flexible to configure; 2. Xen, a paravirtualization technology that can freely load kernel modules and virtualize Memory and IO; 3. KVM, completely virtual, supports any type of operating system.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

Three common virtualization technologies are currently: OpenVZ, Xen, KVM.

OpenVZ (easy to oversell)

operating system level Virtualization technology is a layer of application on the operating system, which means it is easy to understand and heavy overhead. It is more flexible to configure (this gives unscrupulous service providers the opportunity to lower the limit.)

Disadvantages: Since it is based on operating system virtualization, if others use it more, you will lose less. After the memory is down, it will crash and become unstable.

Advantages: The service provider’s licensed memory and CPU are very good.

Xen

is paravirtualization technology, it is not a real virtual machine. It is equivalent to running a kernel instance and can freely load kernel modules, virtual memory and IO. . Xen hvm and Xen hvm pv only support linux hvm supports win system

Advantages: exclusive memory, although it is small, it is all allocated. No matter how low the memory is, it will not crash or become unresponsive for a period of time.

Disadvantages: small memory, small hard disk, and small bandwidth. pv performance is better.

KVM

Advantages: Completely virtual, regardless of the difference between pv and hvm. Supports any type of operating system.

Check the performance of the local VPS to determine whether it is overbooked

How to overbook openVZ VPS:

cd /dev/shm

dd if=/dev/zero of=./memtest bs=1M count =100;//Create a 100MB file

View memory:

free -m

Continuously increase the count value within the specified range (the range you purchased). If the machine crashes within the promised content, it means that the oversold is very serious.

Don’t forget to delete the file you just created after the test rm ./memtest

View CPU information

cat /proc/cpuinfo

Disk IO Test command

dd if=/dev/zero of=test bs=64k count=512 oflag=dsync

1) Check the process memory usage

top

2) View CPU information

cat /proc/cpuinfo

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