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DragonFly bugs List (threaded) for 2005-02
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Re: Off-Topic Question

From: David Rhodus <sdrhodus@xxxxxxxxx>
Date: Wed, 16 Feb 2005 13:03:38 -0500

On Wed, 16 Feb 2005 18:21:21 +0100, Joerg Sonnenberger
<joerg@xxxxxxxxxxxxxxxxx> 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.

                                            Steven David Rhodus

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