Filesystem     Size    Used   Avail Capacity  Mounted on
/dev/ada0p2      1G    624M    302M    67%    /
devfs          1.0k    1.0k      0B   100%    /dev
/dev/ada0p4    503M     20k    463M     0%    /tmp
/dev/ada0p5    9.9G    1.7G    7.3G    19%    /var
/dev/ada0p6    903G    903G    -71G   109%    /usr
devfs          1.0k    1.0k      0B   100%    /var/named/dev
  • please explain your question, don't just put the output of a command – user137124 Apr 13 '16 at 13:56

From your output, the disk /var/dev/ada0p6 seems to be so full that you are now using "reserved space". Usually, 8-10% of disk space are "reserved" (i.e. only root processes can allocate space once disk usage exceeds 90%). Once this happens, free space is reported as a negative number.


The answer above is correct in that the reserved space is being subtracted from that available, leaving you with a negative amount of space usable by non-root users.

You ask how to remove the error. You can either—

  • free disk space;
  • expand the filesystem; or
  • reduce the size of the reserved area.

On an ext3/4 filesystem you use tune2fs to set this percentage like this:

# sudo tune2fs -m 2 /dev/ada0p6

This will set the reserved space to 2% of total disk space. Beware when doing this, as reducing it too far may allow ordinary users to fill the filesystem and cause system-wide problems.

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