Introduction to virtualization features

virtual machine ： Logical processing , A virtual machine consists of files （ The configuration file / Disk files ）

Virtualization features are divided into ： Cluster characteristics and host characteristics

colony ： Combine a group of hosts to form a whole , How to provide resources to users （ Computing resources 、 Storage resources 、 Network resources ）.

host ： A single

Let's introduce the virtualization cluster features

• HA: The high availability feature of the cluster , Overcome the limitations of a single host , When a physical host fails, the business will not be interrupted or the time will be reduced , Clusters generally require shared storage .

• Load balancing ： Share specific services to multiple devices or links , So as to improve the business processing ability .

advantage ：

High performance ： Distribute business evenly to multiple devices , Improve overall performance .

Expansibility ： Load balancing technology can easily increase the number of devices or links in the cluster .

high reliability ： Single or even multiple devices fail , It will not lead to business interruption .

manageability ： Administrators can facilitate centralized management .

transparency ： Transparent to users , Users do not perceive or need to know the network structure .

• Easy to expand ： In virtualization , All resources hosting the business virtual machine come from the resource pool , When business development needs to enhance resources , Just increase the resources in the resource pool .

• Memory reuse ： When the physical server resources are certain , By comprehensively using the single technology of memory reuse （ Memory bubble 、 Memory replacement 、 Memory sharing ） Time division multiplexing of memory , Make the virtual machine memory The sum of specifications is greater than the memory specification of the physical server .

Memory bubble ： The system actively reclaims the memory temporarily unused by the virtual machine , Assign to virtual machines that need to be used . Memory is recycled and evenly distributed for automatic execution by the system , Virtual machines are not aware .

Memory replacement ： Replace the memory capacity of the virtual machine that has not been accessed for a long time into the external storage , And establish a mapping relationship , When virtual machines need to be used , In exchange .

Memory sharing ： Multiple virtual machines share the same physical memory space , At this time, the virtual machine only performs read-only operations on the memory , When the virtual machine needs to write to memory , In addition, open up a memory space , And modify the mapping .

Memory reuse value ：

1. When the amount of memory of the computing node is fixed , It can increase the number of virtual machines on the computing node
2. When the number of virtual machines on the computing node is certain , It can save the amount of memory of the node

Next, we introduce the characteristics of virtual machine

Rapid deployment of virtual machines ： The rapid deployment of virtual machines can be realized by template or cloning .

Template deployment virtual machine ： Template is also a virtual machine in essence , It also contains disk files and configuration files . Using templates can save time in configuring new virtual machines and installing operating systems , The virtual machines deployed by the template are independent of each other , Suitable for mass deployment of virtual machines . It can ensure the consistency of virtual machine system , At the same time, it can also remove differential parameters （IP、SID、MAC）.

Virtual machine cloning ： Quickly deploy a virtual machine using the virtual machine itself , Virtual machine cloning is the complete replication of the original virtual machine at a certain point in time . The virtual machine is as like as two peas. , Include IP、SID、MAC.

Hot addition of virtual machine resources ： When the virtual machine is in the power on state, increase the calculation of the virtual machine 、 Storage 、 Network and other resources .

The virtual machine console control ： A network that can be independent of virtual machines , Control and manage virtual machines .

Snapshot of the virtual machine ： A snapshot is a fully available copy of a specific dataset of a virtual machine , The dataset contains a static image of the data at the copy point . It is generally used to upgrade virtual machines , patch up 、 Before destructive operations such as testing , Once the virtual machine fails , Fast recovery through snapshots .

The snapshot management ： establish 、 Delete 、 recovery 、 Import 、 export

Snapshot mode

ROW（ When writing copy ）： When you need to write , Write directly to the log , When reading the original volume , First retrieve the log ; When reading a snapshot , The original volume needs to be referenced .

COW（ Copy before writing ）： But when you need to write , The original data needs to be copied to a dedicated space and then indexed .

NUMA： Non uniform access to memory , It is a technology to improve the speed of data reading and writing , Use NUMA Technology allows virtual machines to use the same NUMA Node Hardware resources on , To improve the response speed of virtual machines .