(no subject)

[Robert Bonomi]

"Those who think they know it all are really annoying to those of us who do."


> Date: Tue, 21 Jun 2011 20:04:52 +0200
> From: Lokadamus <lokadamus at gmx.de>
>
> Your folder tmp is an own partition with just 1GB size.

FALSE TO FACT.

You can run df(1), giving it _any_ fileneme -- whether OR NOT it is
a directory -- and it will report the statistics for the underlying
filesystem.  Proof:

   %df -H /COPYRIGHT
   Filesystem       Size    Used   Avail Capacity  Mounted on
   /dev/idad0s1a     65M     35M     24M    59%    /
   %ls -l /COPYRIGHT
   -r--r--r--  1 root  wheel  6197 May  1  2009 COPYRIGHT


For this user, /tmp is part of the / filesystem, as is CLEARLY  shown
by the 'Mounted on' field in the df output, below.

The filesystem on 'ard0s1a', =mounted=as='/'=, _is_ roughly 1 gig in size.
The filesystem "overhead" -- primarily the space reserved for (assuming a
UFS filesystem) the FIXED SIZE (and pre-allocated) 'inode table', the 
'backup superblocks', and the cylinder-group metadata -- accounts for the
filesysem 'size' of 989M.  Of that 989M, 8% has been set 'reserved' for 
superuser-only use.

Programs running, with the EUID of 0 (the superuser), were creating the 
problematic /tmp files, thus the negative 'Avail' number, and the 'used'
space being shown as over 100% in the 'Capacity' column.


> Mon Jun 20 11:41:58 2011 849M /tmp 
> Mon Jun 20 11:42:01 2011
> Filesystem   Size   Used   Avail   Capacity   Mounted on
>/dev/amrd0s1a 989M   987M    -76M       108%   /
>
> When a partition is over 100% its use backup place for defect sektors. A 
> partition is/was created with 110% and 10% are for defect sectors.

FALSE TO FACT.

  When 'spare' sectors are allocated for potential defective sector 
  substitution, they are _not_ included in the available space/capacity
  of a filesystem.  With most _modern_ disks, bad-sector substitution
  is handled by the _disk_hardware_itself_, *invisibly* to the host computer
  hardware, *or* operating system.  

  *IF* spare sectors are allocated the O/S for bad-sector management, this
  is done by the 'low level format' utiltity, before any sort of filesystem,
  _if_any_, is created. i.e. there =will= be spares, for bad-sector 
  substitution, even on the portion of a disk used as a 'swap' partition,
  despite there being no filesystem there.

  The 'reserved' space, "traditionally" the last 10% -- although in this case
  of the OP's drive it was _8%_ -- of the filesystem capacity, is set for the
  _exclusive use_ of the superuser, for regular filesystem activity (to wit,
  writing files to it).  The reasn for this 'reserved space' is so that a 
  'regular user' with runaway disk usage, will _not_ be able to cause _system_
  processes to fail for lack of disk space.

  In the OP's case, it _was_ a' superuser process' that was writeing to 
  /tmp, so that process failed _only_ when the space on the filesystem was 
  _TOTALLY_ exhausted, instead of when usage reached '100%' of the file
  system space available to 'regular users'.