Debian 7.6 OpenVZ VPS claims full disk usage when it's clearly not true

Question

I have Debian 7.6 installed on an OpenVZ VPS with 10G hard drive space, but for some reason it claims 100% is used when I'm clearly not using that much. I ran df -h to find out the following:

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/simfs       10G  5.3G     0 100% /
tmpfs            16G  1.1M   16G   1% /run
tmpfs            16G     0   16G   0% /run/lock
tmpfs            16G     0   16G   0% /run/shm

I then deleted some old files to see if it changed anything and used df -h again only to find out that usage is still 100%.

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/simfs       10G  3.9G     0 100% /
tmpfs            16G  1.1M   16G   1% /run
tmpfs            16G     0   16G   0% /run/lock
tmpfs            16G     0   16G   0% /run/shm

The control panel for the VPS says following:

I can delete files but I cannot write anything new. What's up with that? Is another client possibly using up my space on the hard disk causing my operating system to be unable to access that space?

I should also mention that I did a full apt-get update followed by apt-get upgrade last night. Could that have something to do with it?

Answer 1

There is probably some files open by processes, and that is why deleting them haven't freed up the space yet.

So if you have deleted a large logfile or similar, restart the process that was writing to that file.

You may get some more information about which files are open,size and which process is using them with the command lsof.

Answer 2

Your inodes are probably used up: check the inode usage: df -i

EDIT: It may also be that the disk space allocated to the virtual system is 10G, but the underlying filesystem on the host was overcommitted and now has no space left to share amongst the virtual hosts.