VAX-11/780 boot disk

From: Jerome Fine <jhfine_at_idirect.com>
Date: Fri Jan 26 15:54:21 2001

>ajp166 wrote:

> >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
> I had other non RT-11 stuff... Also I have a RT-11 disti that is the high
> priced spread (macro with comments) and that does fill the disk. The
> standard V5.x BIN disti is maybe 30% of the disk.

Jerome Fine replies:

I have been told that starting with V5.05, "the high priced spread" was
split onto 2 RL02 cartridges with each only slightly more than half full.
Which versions of the RT-11 Source distribution do you have? Also,
although the BIN distribution was only about 7000 blocks, the update
distribution for layered products was much less in most cases. So
setting up a DSK file on an RD52 to hold only the actual files from a
distribution would be the most efficient way - short of doing a Zip.

> >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.
> I know. ;) Though a few were partitioned so I could run them as
> if they were nominal RL02. That wastes space if they were to be pure
> archival.

I missed something - or I just don't understand what you are getting at.
What was partitioned - RD52 or RL02 or a much bigger drive? And
I also don't know if "run" means "boot" or something else.

One feature that RT-11 never managed was to enable a DSK file
to be booted. That might be a bit tricky, but should not be impossible.

> >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
> That works. I also have that archive on DLT (TK50).

I tried the TK50 - ONCE. Since I do a verify on any backup tape 99%
of the time, anyone who has tried to do a BUP verify using a TK50
vs a hard disk will understand. While it took about 19 minutes to write
one 32 MByte RT-11 partition, it was over an hour during the
"/VERIFY:ONLY" operation that I gave up.

Now the TK70 (which uses the IDENTICAL DLT tape - CompacTape I)
is another matter. The TK70 drive writes 4 times as much data on one
tape and writes the data three time as fast and the "/VERIFY:ONLY"
operation is just as fast as the BACKUP. So a BUP with the TK70
can place 8.5 RT-11 partitions on one tape using a TK70.

> >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.
> Yep, though the RD52s are likely the most reliable of the pack
> and if the problem is not in the HDA a board swap is possible.
> It was a direct approach.

Reliable - yes. Useful as compared with 256 MBytes - NO!
But if you restrict the comparison to RD51,2,3,4 drives, then
yes!!!!!!!!!! I have had too many RD53 drives go in the last
few years to count. Most were Micropolis 1325 drives with
the R7 jumper inserted so that the RQDX2 thought they were
a real DEC RD53.

But with Hitachi DK515-78 drives and a Sigma RQD11-EC
that handles four drives, there is not much to choose between
4 * RD52 (= 120 MBytes) and 4 * DK515-78 (=2.4 GBytes).

> Next pass will be to move them to a PC with a Cdburner.

Now this is one area I would like to solve as well. But what
OS is needed if I want to use the first 64 blocks on the CD?
And could I take two of the MO cartridges and burn them onto
a single RT-11 bootable CD?

Sincerely yours,

Jerome Fine
Received on Fri Jan 26 2001 - 15:54:21 GMT