Date: Sun, 7 May 2000 17:46:39 +0930 From: Greg Lehey <grog@lemis.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk>, "Justin T. Gibbs" <gibbs@FreeBSD.ORG> Cc: FreeBSD-arch@FreeBSD.ORG Subject: Re: Support for bootable Vinum file systems: please review Message-ID: <20000507174638.E55316@freebie.lemis.com> In-Reply-To: <3924.957523953@critter.freebsd.dk> References: <3175.957561737@critter.freebsd.dk> <200005052141.PAA58901@caspian.plutotech.com> <20000505122100.I32650@freebie.lemis.com> <3924.957523953@critter.freebsd.dk>
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On Friday, 5 May 2000 at 12:52:33 +0200, Poul-Henning Kamp wrote: > >> I've been testing vinum root file systems for a couple of months now, >> and I'd like to commit the code. I'm attaching the patches, which you >> can also access at http://www.FreeBSD.org/~grog/vinum-root.html. > > It looks good, but I think using devstat to find possible disks is > wrong. > > The right way to do it is probably to link the "struct disk"s > registered by the drivers with disk_creat() into a list which can > be searched. This is pretty much what struct devstat does, except that it's more global. Why should we maintain two lists, just because one is primarily intended for statistics? Anyway, I assume this isn't so much a criticism of the fix as of the infrastructure around it. Correct? On Friday, 5 May 2000 at 15:41:34 -0600, Justin T. Gibbs wrote: >> It looks good, but I think using devstat to find possible disks is >> wrong. > > I agree. > > Another thing that is ugly about this is the kludge in the partition > table. I'd rather see us finally bite the bullet and move to an > extensible disklabel scheme. Again, may I take this as a criticism of the infrastructure rather than the fix? > So, in order to have a bootable vinum RAID 1 volume, your partition > entry might look like this: > > > Section 0 > Section Size XXX bytes > Section Type BSD Parition Info > BSD Parition Specific info ... > > Section 1 > Section Size XXX bytes > Section Type Vinum Info > Partition is Part 0 of X parts type RAID 1 > etc. > > Reserved Space for additional Sections > > Actual partition data.... > > So, the bootstrap doesn't need to know how to interpret anything > other than Section 0 and how to skip over other sections to find the > start of data. Once the kernel is loaded, a vinum interrupt driven > configuration hook can scan all known disklabel entries for its > sections and build its plexes on the fly. Hmm. I think it's a little early to discuss how to fix the current disk label problems. Vinum is device ID independent, and it does this by having its own labelling scheme. Mike Smith has already suggested that we should develop it further and use it for generalized disk labelling, but I hadn't planned it for that, and it's not clear that it's suited. > The only additional piece of magic required is stealing root away > from the booted off partition, but I'm sure Greg has already dealt > with that. In fact, I didn't need to. That's what had me worried most, but we can now just go and tell the system which file system to mount. I'm sure that wasn't always the case. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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