Troubleshoot this issue by performing the following steps:
df -h
In this example, the /dev/vda1 partition usage is 100%.
df -i
In this example, the disk space usage is low.
lsof | grep deleted
Roughly calculate the total size of the deleted files based on the returned command output. If it is almost the same as the used space of the disk, the disk space may be used up by the deleted processes that have not been released.
ll /tmp/
Note that variable /tmp/ in the command indicates the path of the deleted file.
kill -9 PID
Note that variable PID in the command indicates the process ID.
lsof | grep deleted
df -h