Subject: Re: FFS journal
To: Bill Studenmund <wrstuden@NetBSD.org>
From: Manuel Bouyer <firstname.lastname@example.org>
Date: 07/05/2006 23:01:27
On Wed, Jul 05, 2006 at 01:31:19PM -0700, Bill Studenmund wrote:
> On Wed, Jul 05, 2006 at 10:20:21PM +0200, Manuel Bouyer wrote:
> > On Wed, Jul 05, 2006 at 12:49:54PM -0700, Jason Thorpe wrote:
> > >
> > > On Jul 5, 2006, at 12:01 PM, Manuel Bouyer wrote:
> > >
> > > >How can we mont it read-only right now ?
> > >
> > > Right now we have ordered MD writes. With a journal, you generally
> > > don't do that
> > I think I explicitely said that we need to keep ordered MD writes for this
> Uhm, the idea of a journal is that you no longer have to order MD writes.
> As I understand it, that is the _point_. To retain ordering when we have a
> journal is defeating the purpose.
Some more though on this: I don't think there can be much performance
difference between a async journaled FFS and a softdeps FFS. And I suspect
it may be easier to add journaling to a softdep FFS, as softdep is a central
point where we have all the metadata writes.
Manuel Bouyer <email@example.com>
NetBSD: 26 ans d'experience feront toujours la difference