On 7 Nov 2017, at 12:54:40 PM, simh-requ...@trailing-edge.com
<mailto:simh-requ...@trailing-edge.com> wrote:
------------------------------
Message: 4
Date: Tue, 7 Nov 2017 20:54:31 +0000
From: Peter Allan <petermal...@gmail.com <mailto:petermal...@gmail.com>>
To: "simh@trailing-edge.com <mailto:simh@trailing-edge.com>"
<simh@trailing-edge.com <mailto:simh@trailing-edge.com>>
Subject: Re: [Simh] Simh Digest, Vol 166, Issue 12
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<mailto:cajcrz55fv2ube5phmtbouxl5yzt8cpyiyhn1cygxghzhbxe...@mail.gmail.com>>
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In order to try to understand why I am having trouble reading a simulated
tape with a simulated TE16 tape drive on a simh VAX 780, I have tried
several configurations.
Firstly, a point of clarification. The problem that I came across was in
finishing the installation of VMS 3.0. This was necessary in order to be
able to install VMS 1.5 using DSC2, but I have no problem with the
installation of VMS 1.5 itself. VMS 1.5 is a red herring - the problem is
with VMS 3.0.
I had configured a VAX 780 in simh with three RP06 disk drives and two
TE16
tape drives. I was using TE16 tape drives rather than TS11 really just
because when I was the system manager of a real 780, it had two TE16 tape
drives.
All of this has been done on a host system running CentOS 5 (for simh
3.8-1) and CentOS 6 (for simh 4.0).
To remind you of the problem, I started the installation of VMS 3.0 by
booting stand-alone backup and restoring a saveset from a tape that I
downloaded from the University of Stuttgart. The first phase went fine and
when I rebooted the 780, the system asked which device contained the
installation media so that it could automatically complete the
installation
of VMS. I entered MTA0: and this is where things went wrong. Wilm
suggested
I should trying using a TS11 drive (MSA0) rather than a TE16 drive and
this
did indeed work, but this left me wondering why?
I have tried to restore a BACKUP saveset from a tape to a disk using
several configurations. I have tried:
- Two difference versions of simh, 3.8-1 and 4.0
- Three different versions of VMS, 3.0, 4.6 and 7.3
- Different simulated tapes
- The two different simulated tape drives, TS11 and TE16
The results have surprised me.
1) Changing the version of simh makes no difference to the results.
2) I only get a problem in restoring a saveset from tape when running
VMS 3.0 as the operating system. Everything works fine with VMS 4.6
and 7.3.
3) I have tried different tapes, but if the system is going to
fail to
do a restore operation, it does it with all of the tapes containing BACKUP
savesets that I tried.
Following a suggestion from Kevin Handy, I tried to copy the savesets from
tape to disk, but the copy failed on the VMS 3.0 system when using a TE16
tape drive.
My experiments indicate that there is a problem with VMS 3.0 when using
TE16 tape drives. However, this seems so unlikely, not least because the
sequence of operations that I have gone through is what hundreds
(thousands
probably) of system managers must have done to install VMS 3.0 on real
hardware, including my predecessor with “my own” 780.
This leaves me stumped, but at least I have narrowed the problem down
and I
am able to do the installation of VMS 3.0 (which lets me do the
installation of 1.5) by using a TS11 drive.
The only thing I can think of is to wonder if the way that VMS handled
TE16
(i.e. massbus) tape drives changed between VMS 3 and VMS 4 and that
somehow
there is a bug in simh that only rears its head on the earlier version. I
confess this is a stab in the dark.
Anyone got a bright idea about this?
Cheers
Peter Allan
