Kubernetes volume management

Kubernetes and Docker use a local host disk by default. The Docker application may store and load any data onto the disk, for example, log data, temporary files, and application data. As long as the host has enough space and the application has necessary permission, data will exist as long as a container exists. In other words, when a container is closed the application exits, crashes, and reassigns a container to another host, and the data will be lost.

Container volume lifecycle

In order to understand Kubernetes volume management, you need to understand the Docker volume lifecycle. The following example is how Docker behaves with a volume when a container restarts:

//run CentOS Container
$ docker run -it centos
    
# ls
anaconda-post.log  dev  home  lib64       media  opt   root  sbin  sys  usr
bin                etc  lib   lost+found  mnt    proc  run   srv   tmp  var

     
//create one file (/I_WAS_HERE) at root directory
# touch /I_WAS_HERE
# ls /
I_WAS_HERE...