No space left on device [closed]
Such difference between the output of du -sh and df -h may happen if some large file has been deleted, but is still opened by some process. Check with the command lsof | grep deleted to see which processes have opened descriptors to deleted files. You can restart the process and the space will be freed.
Maybe you are out of inodes. Try df -i
2591792 136322 2455470 6% /home
/dev/sdb1 1887488 1887488 0 100% /data
Disk used 6% but inode table full.