Appropos my "laughably small" disk space comment, here's a snippet from mkfs.ext4:

       -m reserved-blocks-percentage
              Specify the percentage of the filesystem blocks reserved for the
              super-user.   This  avoids  fragmentation, and allows root-owned
              daemons, such as syslogd(8), to continue to  function  correctly
              after non-privileged processes are prevented from writing to the
              filesystem.  The default percentage is 5%.

I have several 12 TB disks scattered about my house. 5% of 12TB is 600GB. I'm pretty confident that all the spinning (no, tapes aren't spinning) storage at all of Bell Labs in 1975 was less than the reserved space for one of my disks. FWIW, I set "-m 0" for honker disks. -- jpl