>"Zane H. Healy" wrote:
> In some cases I've had to archive the original material, and then reuse the
> original Media (RL02's come to mind).
Jerome Fine replies:
However, if you retain the original Media, then you can always
copy the original material back to the original Media if that ever
becomes necessary and there will never be a problem - although
I presume that the CIA could figure it out if they ever wanted to.
> I'm trying the following with my archive of DEC stuff.
> 1. I have the archive on my fileserver (I prefer keeping copies on two
> different spinning hard drives).
> 2. I have two backup copies, one I keep, and one my parents keep.
> 3. I update #2 when additions are made to #1, keeping the previous backups.
I have also added one additional aspect to saving RL02 images
when I want to keep a backup in RT-11. Since the maximum
size of an MSCP device is 32 MBytes and an RL02 image is
10 MBytes, ONLY 3 will fit into one MSCP device.
HOWEVER, I really can't see any point in keeping a full RL02
image when in many (most) cases, the latter portion of an RL02
image is all zeros - especially when an RL02 was used as a
distribution media. In RT-11, that adds a lot of useless blocks.
The solution I have used is to retain ONLY the blocks with useful
information and discard all the blocks filled with zeros starting with
block 20449 and working backward until a non-zero block is
encountered. In many cases, this means that I am able to put
between 15 an 20 RL02 images into one MSCP RT-11 partition
without any loss of information.
One other suggestion for those who are saving the RL02 images
to a CD. Make the total number of blocks saved an exact multiple
of 4 blocks - on a CD, every new file starts on a sector boundary.
This suggestion is very useful when the following paragraph is
considered.
Also for a CD, I am able to set up an RT-11 file directory for at
least RT-11 partition zero for all of the files copied to the CD
under the ISO9660 file structure. I am attempting to find a simple
way to do the same for files that are in non-zero RT-11 partitions
on the CD, but thus far have not been very successful. However,
as long as the total size of all the files saved to the CD is less than
300 MBytes, there is no problem in duplicating the files and copying
then to RT-11 partitions at the end of the CD. Tim Shoppa did this
with the RT-11 Freeware CD.
It is also possible to produce an RT-11 bootable CD using a DSK
file that is totally in RT-11 partition zero which was originally placed
in the CD under the ISO9660 file structure - assuming that the DSK
file contains a set of RT-11 bootable files that can run using an MSCP
controller - since I don't know of any CDROM drives on a real DEC
PDP-11 that are not SCSI.
Sincerely yours,
Jerome Fine
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Received on Mon May 12 2003 - 22:04:00 BST