[Simh] Using an ODS-2 physical SCSI drive with simh

[Mark Pizzolato - Info Comm]

Hi Peter,

It ‘should’ work just fine, but Christian’s suggestions to work from a copy are quite reasonable.

The latest simh code from github can be used to make this copy for you:

    sim> set rq2 rauser
    sim> ! On Windows
    sim> attach rq2 –fc raw Raw-Disk-Image.vhd \\.\PhysicalDrive1
    sim> ! On Linux
    sim> attach rq2 –fc raw Raw-Disk-Image.vhd /dev/sdb


-        Mark

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Christian Brunschen
Sent: Sunday, June 28, 2015 3:56 AM
To: Peter Allan
Cc: simh at trailing-edge.com
Subject: Re: [Simh] Using an ODS-2 physical SCSI drive with simh

If you have the option to do so, I would suggest making a byte-by-byte dump of the contents of the drive (a disk image), and putting that disk image somewhere safe and read-only; then, use a copy of that disk image for any experimentation. That way you're firstly reducing any wear on the drive itself, only reading data from it, once; and you're not risking any damage to the data, since you're working on a copy of the original which is safely stored elsewhere, and you can always start over with a fresh copy of the original at any point.

Also, if your host computer is fairly modern, a disk image may actually be a lot faster to access than the original SCSI drive.

// Christian


On 28 June 2015 at 11:38, Peter Allan <petermallan at gmail.com<mailto:petermallan at gmail.com>> wrote:
I know that you can use a physical SCSI drive with simh by using the RAW device. However, before doing so, I want to check something.

The drive that I have is a 9GB SCSI drive that was formatted and written to on an Alpha workstation that runs VMS 7.2-1. The disk structure on the drive is ODS-2.

My question is - will using the drive as a RAW drive in simh let me access the existing file structure on the disk? I want to use the vax (microVAX 3900) simulator.

Is it safe to write to the drive or might that mangle the file structure?

Are there "gotchas" to watch out for, such as needing to tell simh the exact size of the drive?

All comments gratefully received.

Peter Allan

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