{"id":605,"date":"2016-06-10T10:48:35","date_gmt":"2016-06-10T10:48:35","guid":{"rendered":"http:\/\/avitech.com.au\/?p=605"},"modified":"2016-08-13T06:39:06","modified_gmt":"2016-08-13T06:39:06","slug":"archiving-dec-vms-cds","status":"publish","type":"post","link":"https:\/\/avitech.com.au\/?p=605","title":{"rendered":"Imaging DEC VAX\/VMS CDs"},"content":{"rendered":"

\"vaxvms061cd\"<\/a>I have some original VMS CDROMs. I was looking for a way to image these (for use with SIMH) and also a way to write ISO images back to blank CDs, to use on real hardware. This should be a fairly simple process using a modern Linux computer and the “dd” command, except for one anticipated complication: “block size”.<\/p>\n

The problem (or what I thought would be a problem) is that VAX\/VMS CDs use a block size of 512 bytes, whereas a PC CDROM drive uses a block size of 2048 bytes. So I was expecting that I would need to hookup an older-style DEC CDROM drive (such as the RRD42) to a SCSI card on the PC, in order to image the DEC CDs. But because the DEC CD drives are read-only, how would I make CDs from ISO images, to use on real hardware, without a CD\/DVD writer that supports a block size of 512?<\/p>\n

Well it turns out that the solution is easier than I expected. My “imaging station” for this experiment is a Dell Optiplex 780 with an internal SATA CD\/DVD drive, running Ubuntu 14.04. Ubuntu reports that the drive is a “PLDS DVD+\/-RW DH-16AAS”. This was a low-cost (approx $300) system that I bought second hand a few years ago.<\/p>\n

What I’ve found is that the PLDS drive seems to be able to detect the block size and switch to 512-byte mode to successfully image a VMS distribution CDROM. Either that, or block size is irrelevant when reading and writing ISO images.\u00a0 I’m really not sure at this point.\u00a0 Either way, it seems there’s no need for a SCSI interface board, or a SCSI CDROM R\/W drive. I don’t know if this capability of the PLDS drive is unusual, or whether most “modern” CD\/DVD drives in budget desktop systems can do this.<\/p>\n

More details are provided below.<\/p>\n

Finding the CDROM device name in Ubuntu<\/h4>\n

The “lsscsi” command can be used to view all SCSI drives connected to an Ubunutu system. On my Dell Optiplex 780, this command also lists all connected SATA drives.<\/p>\n

Here’s what the command shows on my system:<\/p>\n

\r\nmalcolm@malcolm-OptiPlex-780:~$ lsscsi \u2936<\/span>\r\n[0:0:0:0]    disk    ATA      ST3160318AS      CC45  \/dev\/sda \r\n[1:0:0:0]    cd\/dvd  PLDS     DVD+-RW DH-16AAS JD12  \/dev\/sr0 \r\n[6:0:4:0]    cd\/dvd  DEC      RRD43   (C) DEC  1084  \/dev\/sr1 \r\nmalcolm@malcolm-OptiPlex-780:~$ \r\n<\/pre>\n
On my system, the internal SATA CD\/DVD drive always appears as \/dev\/sr0.<\/p>\n
My system also has an Adaptec AHA-2930CU internal SCSI adapter installed. When I connect an external SCSI CD reader to the AHA-2930CU, it shows up at \/dev\/sr1. But Ubuntu has to be power cycled for it to show up.<\/p>\n
The external  CD reader that I’ve been using is a RRD43. Unlike the RRD42, it doesn’t require a caddy. And unlike the RRD46, it doesn’t have a motorised tray. Instead, when you press the eject button, the tray pops open about an inch. You then manually open it from there, and close it again.<\/p>\n
I usually use the internal PLDS drive for imaging VMS CDs, because of its convenience. But I’ve also had success in imaging the same CDs using the external RRD43 CD reader. But the RRD43 (connected to my AHA-2930CU interface) is much slower. I found that a 624MB CD takes 337 seconds (1.9 MB\/s) to image using the internal PLDS drive. The same operation with the same CD on the external RRD43 takes 2038 seconds (306 kB\/s).<\/p>\n
Ejecting a CD from the external RRD43 drive<\/h4>\n
I sometimes find that I can’t eject a CD by pressing the eject button on the front of the RD43.<\/p>\n
When this happens, I just use the eject command, which works just fine.  Here’s an example:<\/p>\n
\r\nmalcolm@malcolm-OptiPlex-780:~$ eject \/dev\/sr1 \u2936<\/span>\r\nmalcolm@malcolm-OptiPlex-780:~$\r\n<\/pre>\n
Imaging a VAX\/VMS 6.1 CDROM<\/h4>\n
\"vms061cover\"<\/a>My distribution of OpenVMS Version 6.1 is a 3-CD set in a 2-CD case (identical to what an audio double-CD set used to be distributed). Opening the front of the case provides access to the first two CDs. The third CD, and the various brochures distributed with the CDs, is via the back of the case.<\/p>\n
The 3 CDs are:<\/p>\n