Reserved space (WAS: How to calculate bsdlabel size)

[Peter Jeremy]

On Fri, Feb 06, 2004 at 09:44:58AM +0100, Claus Guttesen wrote:
>>> But it's not my problem. What you mean results in
>>> limited available space,
>>> but doesn't have any influence on Size summary.
>>> Btw I did a newfs with -m 0
>>> so it can't be the reaseon.
>> 
>> This is strongly non-recommended.  The UFS
>> algorithms are designed on
>> the assumption that there are always free blocks. 
>> When you get below
>> 5-10% free space, the performance will degrade
>> significantly and you
>> will start getting file fragmentation.
>> 
>
>Does the algorithm(s) rely only on percentage of free
>space? On a five TB (netto) filesystem eigth percent
>is approx. 410 GB which seems quite alot.

In general, yes.  See /usr/share/doc/smm/05.fastfs/paper.ascii.gz
You might be able to get away with a lower minfree in some circumstances
depending on your filesystem activity pattern.

Peter