Weird OVZ behavior
First of all, I don't take this against my host, as bad things can really go wrong, its part of life.
The problem: 2 weeks ago, I got an OVZ and installed debian6, NLMP and a single wordpress website, whose files are in /home/jon/public_html. Owner of public_html and all child contents are jon:www-data, and permission is 770. All is working fine and I can access website and do stuff and all.
Then after a day, suddenly the site can't be accessed. I also cant SSH to the VPS. After 2 hours, website shows nginx error, but I can ssh. Upon SSH as user jon, I can't access the files inside public_html via ls, cat, nano, etc. When I changed user to root, I can view the files, and indeed owner and permission did not change at all, still jon:www-data and 770. When I did chmod 777 to the files, I can access it again and website is working. When changed back to 770, the problem occurs.
What I did is just removed and recreated public_html and put necessary files from backup in another vps. Changed to 770, and it works.
I am not sure what happened, but it did scared me using OpenVZ.