[OpenAFS] Changing reserved block on ext3 with fs running

Stephan Wonczak a0033@rrz.uni-koeln.de
Wed, 5 Oct 2005 14:16:52 +0200 (MET DST)


On Wed, 5 Oct 2005, Frank Burkhardt wrote:

> >   Now the question: Are there any repercussions when changing the number
> > of reserved blocks in this way, or are there any subtle side effects on
> > the fileserver?
> AFAIK there should be no problem using 'tune2fs -r' or 'tune2fs -m' on
> a mounted filesystem (I just tried it).

  'Should' is a word we are very reluctant to use in a production
environment :-)

> But you most probably needn't do that. The reserved blocks are only
> accessible to a given user (see 'tune2fs -l /dev/ice | grep uid') when the
> limit is reached. But this given user is root by default and AFS-Fileservers
> are running as root. Reserved blocks simply don't matter in this case.

  Well, in principle you are correct. But the fileserver seems to use only
the non-reserved blocks (you can check this with vos partinfo). So the fs
will report 'no space left' even if the reserved blocks are available.
There is nothing wrong with this behavior, actually this is correct as far
as I am concerned (this way root has a chance of some cleanup even if the
fs started to scribble like mad).
  So the question remains: Any nasty sideffects on changing the number of
reserved blocks and thus the usable capacity of a vice partition while the
fileserver is running?

	Dipl. Chem. Dr. Stephan Wonczak

        Zentrum fuer Angewandte Informatik (ZAIK)
        Regionales Rechenzentrum der Universitaet zu Koeln (RRZK)
        Universitaet zu Koeln, Robert-Koch-Strasse 10, 50931 Koeln
        Tel: ++49/(0)221/478-5577, Fax: ++49/(0)221/478-5590