Date: Thu, 21 Jan 1999 11:58:13 +1100 (EST) From: "John Saunders" <john.saunders@nlc.net.au> To: Mike Smith <mike@smith.net.au> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Booting -current with new loader Message-ID: <Pine.LNX.3.95.990121114034.29987E-100000@nhj.nlc.net.au> In-Reply-To: <199901202027.MAA01089@dingo.cdrom.com>
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On Wed, 20 Jan 1999, Mike Smith wrote:
> > The option of putting the second drive
> > as slave on the primary interface would work, however anybody that knows
> > anything about IDE (read somebdy interested in trying FreeBSD) would put
> > it on the second interface for speed reasons.
>
> Er, you want to stop and think about that for a second? If you have
> Windows on one disk and FreeBSD on the other, where is the opportiunity
> for drive conflicts (the source of performance loss)?
In the context of one disk totally Windows and the other totally FreeBSD
then yes you are correct. However I have a 1 Gig partition at the end of
both disks that I have a CCD mirror on. Read performance won't suffer by
moving the drive but write performance halves. Actually I have intended to
modify CCD so that is distributes reads over all devices in the mirror, I
noticed that it simply hammers the first drive. I'm not sure if core would
be interested in such a patch since I think vinum is taking over.
That's why I shy away from moving my hardware around. Also I would have to
break out the screw driver, when all I need is some finger work.
> > I'm not sure about anybody else here, but to my mind a "Winblows on C:
> > drive and let's try out FreeBSD on the second disk" configuration should
> > really be supported seamlessly.
>
> You're more than welcome to propose a technical solution that solves
> the problem.
OK, the technical solution that I propose is an alternative (optional
because I want to retain the current semantics) config semantics.
controller wdc0 at isa? port "IO_WD1" bio irq 14 flags 0xa0ffa0ff
controller wdc1 at isa? port "IO_WD2" bio irq 15 flags 0xa0ffa0ff
disk wd? at wdc?
This would act identical to the way the SCSI system works by assigning
names to disks as they get probed. It would also have the advantage of
assigning disk names in the same order as the BIOS (and thereby the boot
loader), hence there would be a 1 to 1 mapping between what the boot
loader uses and what the FreeBSD kernel detects.
I believe the current problem stems from the BIOS (and thereby the boot
loader) and the FreeBSD kernel assigning names using a different algorithm
and then getting out of step when the kernel skips a name.
If anybody knows how to do this quickly then I am happy to help test it.
Cheers.
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