Subject: Re: Journaling for FFS
To: Manuel Bouyer <bouyer@antioche.eu.org>
From: Bill Studenmund <wrstuden@netbsd.org>
List: tech-kern
Date: 10/02/2006 12:56:25
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On Mon, Oct 02, 2006 at 09:16:29PM +0200, Manuel Bouyer wrote:
> On Mon, Oct 02, 2006 at 09:09:49PM +0200, Jochen Kunz wrote:
> > On Mon, 2 Oct 2006 09:26:04 -0700
> > Bill Studenmund <wrstuden@netbsd.org> wrote:
> >=20
> > > If someone wants to work on journaling for ffs, please don't
> > > discourage  him or her.
> > >=20
> > > LFS and FFS work well for different work loads. There are workloads
> > > for  which either one of them will blow the other away. As such,
> > > neither one  will replace the other for performance use under certain
> > > workloads; we  need both.
> > This is a good point. I didn't think of this. The same for Jorgen
> > Lundman's remark about adding jornaling to FFS like a mount option just
> > like softdeps.
> >=20
> > Matt: Go for it! :-)
> > (One thing to take into consideration: It may be more valuable to have
> > jornaling for FFSv2 first, then for FFSv1. A FFSv2 can be much larger
> > then a FFSv1...)
>=20
> I'm not sure it makes a big difference supporing only one, or both.

Depends on how you do it. If you go for a physical block journal, it's the=
=20
same for FFS1 and FFS2. A logical journal (which I dislike, but wouldn't=20
block if it showed up as a complete thing) will be different. Well,=20
journal replay will care.

Take care,

Bill

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