Finding used space on CentOS
Solution 1:
Often times when something like this happens, it is due to some process keeping filehandles open on deleted (unlinked) files. If this is the case, you can find them by using lsof, for example:
$ sudo lsof +L1
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NLINK NODE NAME
tuned 869 root 7u REG 202,1 4096 0 4194380 /tmp/ffiGemRJt (deleted)
$
If you find deleted files are consuming much of your space, then it will probably be necessary to restart the offending process that is keeping the filehandles open.