Hi You can check the installed version by simply running nova-manage version . You will get a date, which correspond to openstack releases. Check the release history here https://wiki.openstack.org/wiki/Releases and compare with your version and click on a release for a more precise display. For example if you get 2014.1.1, it correspond to the Icehouse June vesion, therefore you have installed the Icehouse release of nova.

Regards.