"netbsd@mrynet.com" wrote:

>   8. FAQ. What is the largest disk I can put on a mVAX.
>      Ans. The system disk is limited to 1 gig (there is a addressing
>      limitation in the boot prom.) Non-system disks are limited to 8 gigs.
>
>This may have been a VMS limitation at one point, but certainly not with
>OpenVMS 7.2 which I run as well,  I have both 1.5 and 4gb drives on a 
>Vaxstation, and a 1.5gb VMS drive on a MicroVax II.

The firmware disk driver in some machines uses SCSI commands that "wrap-around"
beyond 1.073GB. This firmware driver is used to initiate the OS boot and is
used until such time as the OS chooses to take over. So if any part of the
booting process needs *anything* that lives beyond 1.073GB into the disk (and
the firware driver is still in use, i.e. the OS has not started to use its own
driver yet) then you are hosed.

For OpenVMS it is relatively easy to get hosed. It's even more complicated
because during a crash dump OpenVMS uses the firmware driver (on the assumption
that it's own could well be broken - it is crashing after all).

For NetBSD it is possible to arrange for everything that matters during booting
to be within the first 1.073GB in which case you should be fine - assuimg you
do this properly of course.

There is no limitation caused by the firmware for non-bootable disks.

The above applies to all VAXstation 3100s and to early variants of the MicroVAX
3100 Model 10 and Model 20. Later variants of the MicroVAX 3100 Model 10 and
Model 20 (any shipped after April 1992 springs to mind) do not have the
limitation. All later MicroVAX 3100s (-30/40/80/85/88/90/95/96/98) do not have
this limitation. None of the VAXstation 4000 series suffer from this
limitation.

Your options for VAXstation 3100s are:
	1. live with it
	2. track down the patches that floated around comp.os.vms last year
	   and blow some new eproms ...



Antonio

>I don't believe the 8gb limitation to be correct anymore either, but I
>don't have tangible proof of that.

OpenVMS used to have a limitation (back in V5.5-2 and before) that prevented it
using drives of > 8.?GB. That has now been lifted to something like 4TB or 8TB
or so.

Antonio