VAX-11/780 boot disk

From: Jerome Fine <jhfine_at_idirect.com>
Date: Thu Jan 25 19:23:12 2001

>ajp166 wrote:

> I did it on my 11/23B. I copied them to RD52s (quantum D540) as they
> are the most rugged drive I know and I had 8 of them free. That's enough
> to hold 24 RL02s and be bootable with RT-11. For safety the most
> important ones are duplicates (used two RD52s as images of each other).
> Testing so far says RD52s have a shelf life of not less than 12 years.

Jerome Fine replies:

Just curious - if you are referring to software distributions and especially
RT-11 (maybe I am confused), in most cases, the RL02 will not be filled
with files. In fact, for RT-11 distributions on an RL02, there were much
less than half full. In that case, it was not necessary to save the portion
of the RL02 past the last file since it would usually just be all zeros in
any case. Under those circumstances, I would look in RT-11 at the
files with the command:
DIRECTORY/FULL/BLOCK DL1:
and find the block number for the <UNUSED> space at the end of the
RL02. Under V5.00 and later, it was very easy (preferred) to CREATE
a Logical Disk "File" with the required size and MOUNT it. Then a simple
COPY/DEVICE DL1: LD1:
would copy all the files to the logical device and a BINCOM after that
DIFF/BINARY/DEVICE DL1: LD1:
would ensure that the copy was correct. This was much better than
COPY/DEVICE/FILES DL1: DU1:SAVRL.DSK
since none of the empty space at the end of the RL02 was wasted.
But you could still reduce the size of the file required to hold an
RL02 that was not full by using the comand:
"COPY/DEVICE DL1:/START:nnn./END:mmm. DL2:/START:ppp."
were nnn., mmm., ppp. are the decimal block numbers, so more than
one RL02 could be saved on each RL02 if they were only half full.

If someone states that they don't at least have V5.00, then you
also can't use the RD52 since DU(X).SYS only became available
with V5.00 of RT-11.

Of course if the RL02 was full, Allison is correct that a single RD52
will hold only 3 RL02 disk packs and in much less volume.

Currently, I have managed to find a very OLD Magneto Optical disk
drive with cartridges that hold 295 MBytes (8.75 RT-11 partitions)
on each side. That is the equivalent of 26 RL02 disk packs on
each side or a total of 52 RL02 disk packs on the MO cartridge
which is about the size and thickness of 4 RX50 floppy diskettes.
I also duplicate important cartridges. I suspect that the MO cartridges
will last longer that the MO disk drives. Of course, I also had to
acquire a SCSI host adapter as well - considerably more costly
than 8 free RD52 drives, but each MO cartridge is MUCH smaller
that the 17 RD52 disk drives it replaces.

Sincerely yours,

Jerome Fine
Received on Thu Jan 25 2001 - 19:23:12 GMT