Brian D. Chase writes:
[...]
> > What is the drive size limit on the boot drive in NetBSD on a MicroVAX
> > 3100?  Can it handle the RZ26 or is that pushing the 1 gig limit too
> > closely?  The RZ26 may work, but I was thinking the RZ26-L was over
> > the edge?  Can someone clarify the limit exactly?
> 
> I'm using a 2GB Micropolis at the boot drive on one of my VAXstation 3100s
> and I've had no problems booting from it.  I know the VMS people have long
> mumbled about the 1GB disk limit for boot drives on the older SCSI VAXen
> like the early MicroVAX and VAXstation 3100 users, but I've yet to run
> into it under NetBSD/vax.

Things are a little bit different for NetBSD and VAX/VMS.
The problems are caused by the firmware using four(?)-byte
SCSI-commands. With NetBSD you have to ensure that bootblocks
and anything else which gets loaded by the firmware is located
below the 1 gig limit. After the kernel is loaded and has taken
control, the limit doesn't exist anymore since the OS is using
six(?)-byte SCSI-commands. Thus the only thing you've to care 
for is the bootable partition (and kernel) is in the first gig
of the disk.
With VMS the filesystem spans the whole disk and the boot device's
firmware-driver is used by the OS. These two things together make
the limit more "real" on this OS. The "wrap-around" happens if
more than 1 gig of the disk is used and thus the first blocks of
the disk are nuked...

Ciao,
	bertram