It was suggested to me that this may be the case: Sometimes it happens that you still have a file handle open to a file that has been deleted.
df -ht shows the disk usage increasing rapidly - like 1 GB per day. du -skh does not show any disk usage increase in areas that i control, except in weird parts like /proc (areas that should not be deleted)
A server restart will free up all the extra used disk usage.
How can I track down the process or file that is responsible for this behavior?