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On Sun, Mar 18, 2007 at 05:36:05PM -0500, Johan A. van Zanten wrote:
>=20
> Bill Stouder-Studenmund <wrstuden@netbsd.org> wrote:
> > On Mon, Mar 12, 2007 at 07:17:13PM +0100, Dieter wrote:
> > > 1) background fsck
> >=20
> > I don't think that background fsck is a good idea. While it'd be nice t=
o=20
> > not have to wait on boot, I think the other options for a fast boot wil=
l=20
> > serve us better. Namely journaling.
>=20
>  There are some applications that would be better served by the use of a
> soft-update-enabled file system.  I'm in the process of building a
> warm-standby backup server for a central file server.  The file server has
> about 1.4 TB of RAID-5 protected storage in two file systems.
>=20
>   Rather than backing up to many, many tapes, and suffering all of the
> problems that entails, i'm planning on backing up to a preferably-NetBSD
> FFS file system, and using snapshots to give access to older data.

> IIRC, LFS does not support snapshots.  FFS does, with soft updates.

That is not exactly correct. Snapshots and soft-updates are not related to
each other, other than that our ffs file system supports both.

A journaled ffs will (well, when done will) have the same snapshot
abilities as a soft-update one.

> Because my understanding of snapshots and soft updates is that it's fairly
> FFS-specific, i'm going to guess that adding snap shots (and soft updates)
> to LFS would be a lot more work than porting the FreeBSD code that enables
> background fsck, though this is just a guess.

If you post (good) patches to add background fsck, I'm not going to throw=
=20
a tantrum and say they shouldn't get added, even though I think that's the=
=20
wrong direction to go. :-)

Soft-updates don't make sense for lfs. Snapshots do.

>  Because of limitations of the file server, i am working with two very
> large file systems: one is ~425 GB, the other is about 1 TB.  So these
> would be backed up to similarly large local (NetBSD) file systems that
> would need to support snap shots, and therefore could not be LFS.

Take care,

Bill

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