Shulou(Shulou.com)05/31 Report--

In this issue, the editor will bring you about how to understand the hot migration implementation of the KVM virtual machine. The article is rich in content and analyzes and describes for you from a professional point of view. I hope you can get something after reading this article.

Question1: why do you need hot migration?

In a cluster, sometimes many virtual machines are installed on a physical server. At this time, the network card bandwidth and disk IO speed of hypervisor will become the bottleneck of each virtual machine on it. At this time, some virtual machines need to be migrated to other machines.

Question 2: how to migrate?

The so-called migration is nothing more than copying the image file and the data in the memory of the virtual machine to another hypervisor, and then another virtual machine on the hypervisor can work instead of this virtual machine.

Question 3: how to copy image?

Case 1: the image file is on the filesystem of hypervisor. You can write your own socket program through scp, but the speed is very slow. If you have an image size of more than 500G, it will take a long time. (it is not recommended to put the image file directly on the hypervisor in the cluster. )

Case 2: the image files are in NFS, SAS and other cluster storage systems. Hypervisor mounts the image file by mounting the image file, so when doing a hot migration, you only need to mount (mount) the folder shared by NFS and SAS on another hypervisor, so that the data is equivalent to the copy of case 1, and the copy is finished in an instant.

The architecture diagram is as follows: (before migration)

The architecture diagram is as follows: (after migration)

As can be seen above, the image files have not been moved before and after the migration, and they are still in the NFS storage system, but are just taken over and operated by another hepervisor.

The above is how to understand the hot migration of KVM virtual machines. If you happen to have similar doubts, you might as well refer to the above analysis. If you want to know more about it, you are welcome to follow the industry information channel.

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