Django PostgreSQL : migrating database to a different directory
Ok, thanks for your answers, I used : 
find . -name "postgresql.conf" to find the configuration find, which was located into the "/etc/postgresql/9.3/main" folder. There is also pg_lsclusters if you want to show the directory data.
Then I edited that file putting the new path, restarted postgres and imported my old DB.
I have a Django website running on an Amazon EC2 instance. I want to add an EBS. In order to do that, I need to change the location of my PGDATA directory if I understand well. The new PGDATA path should be something like /vol/mydir/blabla.
I absolutely need to keep the data safe (some kind of dump could be useful). 
Do you have any clues on how I can do that ? I can't seem to find anything relevant on the internet.
Thanks