this command adding 50G to existing container or it's create container?
vzctl set 111 --diskspace 50G:50G --save
this command adding 50G to existing container or it's create container?
vzctl set 111 --diskspace 50G:50G --save
your command is setting the soft- and hard- diskspacelimit of the existing container: 111 to 50G.
For creating a container use vzctl create or prlctl create.