After using the instructions I found on http://www.unixmen.com/install-and-configure-openvz-in-ubuntu/ I installed OpenVZ on Ubuntu 14.04 LTS, which is running in WMware Workstation 10.0.3. Then I moved to http://www.unixmen.com/how-to-create-openvz-container-in-openvz/.
In the tutorial, they download CentOS 7, but because I can't use 64-bit versions under my VMware Workstation (due to an option unavailable in my BIOS), I chose to download an older, 32-bit version of CentOS. I unpacked the .tar file after download.
When I entered the command
root@box1:/etc/vz/template/cache# vzctl create 101 --ostemplate centos-6-x86
to create the first virtual machine I get these:
Warning: CT config file already exists, not applying a default config sample.
It might lead to incomplete CT configuration, you can use --applyconfig to fix.
Error: diskspace not set (required for ploop)
Creation of container private area failed
Why do I get that error? Is there something to be done about it?