Subject: Re: Possible summer of code project: Logical Volume Manager (request for comments!)
To: None <tech-kern@netbsd.org>
From: Bill Studenmund <wrstuden@netbsd.org>
List: tech-kern
Date: 06/06/2005 11:36:56
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On Sat, Jun 04, 2005 at 05:51:10PM -0400, Allen Briggs wrote:
> On Sat, Jun 04, 2005 at 09:04:44PM +0800, Cameron Patrick wrote:
> > I'm thinking of porting (or perhaps reimplementing :-/) Linux's
> > Logical Volume Manager to NetBSD as a Google Summer of Code project.
>=20
> You've done a bit of this below, but I would encourage you to think
> not so much in terms of porting/reimplementing, but in terms of
> filling needs. What features do you want to have, and what's the
> best way to get them?
>=20
> Something else to look at might be FreeBSD's GEOM. I don't know
> much about it--just seen passing references to it. I get the
> impression that it at least has some overlap with an LVM.
This LVM sounds like IBM's LVM which was in AIX. I used that in the early=
=20
and mid 90's, and it was very cool. It has a lot of features, an=20
established track record, and I think being disk-compatible with Linux is=
=20
a good thing. Some new file systems are getting stacked on top of LVM, so=
=20
being able to use it would be good.
> As someone already mentioned, you might want to look at NetBSD's
> 'wedges', too. Wedges are a fairly new thing in NetBSD and not
> fully exploited yet.
I expect that the best way for an LVM port to expose the LVs is as wedges.
> As for the root on LVM, it seems that the device mapper would
> want to perform an autodiscovery phase like RAIDframe does.
> I.e., after the physical disks are enumerated, look for the
> information to configure any LVs. I think that's what you're
> suggesting.
I agree. We already have hooks to let RAIDframe run before init does (and=
=20
yet have init keep pid "1").
Take care,
Bill
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