Error write failed/Filesystem full

Hello community.
I have one problem with my server that is online. My server is online and everyday i have 120+ players online. I have a good host with 12gb ram. But some times the server shutdown. Every player get kicked and when they try to connect they get Fail to connect to the server. Then i reboot the freebsd, i try to start my server again and then i get mysql error, that mysql is not running. Then when i try mysqld_safe i get this error "write failed/Filesystem full". Why is this happening?
Can anyone help me? or find a solution to fix this problem?

Your harddrive / partition is full.... im pretty sure your logs in the cores (for example /home/game/channel1/***/syserr and sys.log) are very big

Also make sure to look where u exactly mounted your partitions.
Often the largest partition, which should be used by the user, is mounted on /home and not on /
so check where u put your files.

Type df -h to see all mounted devices. It also shows you size, available storage and used storage