As far as I know you can't boot a traditional
VAX from a disk of
<1GB... but could I put the core of VMS on a small slow narrow SCSI
disk, like an
80MB or something, and put most of it on the only Wide SCSI disk I
have, a 10GB...?
You can use a sub-1GB disk to boot from, yes. Booting is, as I
understand it, the only restriction.
Booting is not the only restriction. As far as I know, the same low
level drivers in the ROM that are used for booting are also used
for writing crashdumps. The problem is that short (6byte?) SCSI
commands are used and the addresses wrap back to zero when trying to
address parts of the disk beyond the 1.0something GB point.
This means that if a dumpfile is located further out than that
point on a large disk that VMS has otherwise successfully been installed
on, it is possible to end up getting the lower part of the disk
overwritten by a crashdump if the system should crash.
It is possible to install a minimal VMS configuration on a small disk
and access data on a disk larger than 1GB. However, it is difficult to
use the larger disk to expand the VMS system as DEC software often
wants to be installed on the system disk, ie the one that booted the
system. The difficulties can sometimes be overcome but it may take
an experienced VMS hacker to do this.
I think the best idea is to get something like an RZ26 disk which is
around 1GB and use that. It is also possible to boot the 3100 remotely
from another VMS system but this is probably not an
option here.
Regards,
Peter Coghlan.