On Wed, 16 Feb 2005 18:21:21 +0100, Joerg Sonnenberger
<joerg@britannica.bec.de> wrote:
> On Wed, Feb 16, 2005 at 06:09:48PM +0100, Tom Hummel wrote:
> > Can you point me to the necessity of adding journaling to UFS? I thought
> > Softdeps haven been a comparable solution to the same problem journaling
> > addresses. Both's performance penaltys over async metadata writes seem
> > to happen in the same universe.
>
> (a) softdep is complex. *very* complex.
> (b) softdep doesn't solve the problems of fast reboots after crash
> (c) softdep doesn't allow replaying changes for off-site synchronisation
>
> I consider softdep a useful concept for a filesystem, it can really
> help for those filesystems we can't add a journaling later on top.
> But having native journaling support can be much better.
>
> Joerg
>
Soft updates and journaling are not the same thing. I haven't done
any testing yet but I don't think FFS would perform as a very good
modern filesystem if we remove soft updates without changing the
behaviour of the filesystem.
--
-David
Steven David Rhodus
<drhodus@machdep.com>