Why is my game discussion forum causing 100% disk usage on my VPS?

Disk 100%, no traffic? Some log file, caching issue or bot must be thrashing the disk. Check your logs - lots of queries from odd user-agents or IP addresses? Bots scraping your forum/wiki? Caching plugin? It could just be writing out to the cache all the time. Database could also be the cause (your forum is making lots of tiny requests against the db, causing 100% IO). Cron job/script gone bad maybe? Look with iotop/htop what's writing to disk. You may have old logfiles too. They can get very big. With phpbb, automated backups and search indexing could also be the cause. Low traffic, high IO = background activity. Hope that helps.

But why 100% disk usage? Perhaps from log files. Perhaps from server cache. Perhaps from bots crawling your forum? Do you have any scripts getting hammered? Have a look in /var/log/apache2/… (or wherever) and see what’s happening. Do you have caching enabled (mod_disk_cache)? If so, disable it, or set up log rotation. Or try `iotop`. Is the disk being used up by some script or other program? You may need to change permissions on that script, or move it off the disk. Do you need to change .htaccess to limit bandwidth usage or block aggressive bots?

Your game forum has high disk activity? Don’t laugh; it is most likely due to automated bots that have been indexing your forums non-stop, especially if you have casino games or sexy content. Verify if you are generating a lot of logs (Apache/Nginx can grow huge, very rapidly); cron jobs performing background tasks with no limit on the size of log files. Install fail2ban so that you don’t allow abusers to fill up your disks and monitor disk activity.