Subject: Re: Log area on-disk for the journal
To: Michael van Elst <mlelstv@serpens.de>
From: Bill Studenmund <wrstuden@netbsd.org>
List: tech-kern
Date: 10/24/2006 11:26:41
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On Tue, Oct 24, 2006 at 07:07:38AM +0200, Michael van Elst wrote:
> On Mon, Oct 23, 2006 at 05:16:14PM -0700, Bill Studenmund wrote:
>=20
> > But that's the point of journaling.
>=20
> To me the whole point of journaling is to avoid costly fsck operations.
> You don't need to weaken file system consistency when you introduce
> journaling.

Well, that's not what it is to a lot of other folks.

Also, think hard about exactly what it would mean if we didn't do the=20
journaling as I describe. If we _don't_ remove all of the sequence points,=
=20
we have both all of the sequence points from before and ALSO we have a=20
two-stage commit! So things are even slower!

On a journaled fs, the journal is an integral part of the fs consistency.=
=20
I'm not coming up with a great way to express this, but the journal is as=
=20
key a part of consistency as the super blocks or the inodes.

Take care,

Bill

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