Subject: Re: Large Disks / Clean Install
To: None <>
From: None <>
List: current-users
Date: 02/08/1999 12:16:40
> > If the new large disk to be labeled has no preexisting BSD
> > disklabel (as is common), sysinst will get a "fictitious"
> > disk label from the OS when it fetches the disk label
> > information (via ioctl, I think).  The geometry of this label
> > will also be cropped to 16383 cylinders, and this will in
> > most cases restrict the available space to a little under
> > 8GB.
> Is the number total of sectors also cropped?

No, it isn't:

wd1 at pciide0 channel 1 drive 0: <IBM-DTTA-351010>
wd1: drive supports 16-sector pio transfers, lba addressing
wd1: 9671MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 19807200 sectors

> If not it should be easy to fix this in sysinst.

I agree.

> > I've found out that it is in most cases asking for trouble to
> > try to bump up the number of heads to get at the additional
> > space, especially if the number of heads in the disklabel
> > doesn't match what the BIOS thinks about the same variable.
> > (Bad things will most likely happen in the bootstrap code.)
> You should just increase the number of cylinders. Leave the
> other geometry parameter as they are.

Yep, exactly my experience.  However, sysinst lets you freely
hose yourself by tweaking the heads/sectors too. ;-)

(Ok, I agree, there's more to it than that, as both the mbr
partition table geometry, the BIOS geometry and the disklabel
geometry play into this.  It looks like sysinst gets its "BIOS"
geometry from fdisk, which in turns uses the mbr partition table,
which may not coincide with what the BIOS actually thinks (?)...)

> This should work if you use the upper part of the disk for
> NetBSD (Then the NetBSD partition can end at 8Gb, but
> partitions in the disklabel can go further), and the root
> partition is below to 8Gb limit.  I don't know how to handle
> boot partitions past the 8Gb limit, or non-netbsd partitions
> past the 8Gb limit (is fdisk able to handle this now)?

Don't know about how fdisk does this -- some information on the
web indicated that one could use "fdisk /x" to turn on (or off?)
the use of int13 extensions.  This fdisk is probably the one
which comes with Windows95 -- the old MS-DOS fdisk doesn't know
about the /x flag.

I think it's sort of a reasonable limitation that your boot
partition part of NetBSD has to reside within the first 8GB of a
drive, and we should document that limitation and implement
something in sysinst which prevents the user from putting himself
in violation of that limitation.

> I installed NetBSD on a 9Gb scsi disk without trouble.  I used
> the whole disk for NetBSD, so sysinst created a 8Gb partition
> on it, but in the disklabel I of course use the whole disk.

Right.  But I guess you had to do like me, i.e. label the disk by
hand first, because otherwise sysinst by itself could not do the
job (?).

- H=E5vard