How does filling a disk to capacity affect performance?

[David Keppel]

In article <92 at iravcl.ira.uka.de> fsinf at iravcl.ira.uka.de writes:
>czei at osupyr.mast.ohio-state.edu (Michael S Czeiszperger) writes:
>>[ df says 100%, really only 90%.  Rationalle: performance ]
>[ crash if full ]

There is a tech report from Berkeley about the FFS (fast file system)
and some mumbling about performance vs. full.  I have the paper at home
but it has been a while since I read it.  I think it is worthwile
reading if you can find a copy.

My local guru says that the packing algorithm for multi-block files
tries to put things together in a pattern that give fast sequential
access.  If there are very few free blocks, then the file system
manager is forced to allocate whatever blocks might happen to be
around, even if they are a large seek (+settling+latency) time away.

	;-D on  ( But then there's always paper tape )  Pardo