Teo Zenios wrote:
A while back there was talk about the life of CDR's
for archives, how do
Magnetic Optical Disks (MO) work for archives?
I recently got my hands on a 1.3GB 5.25" Olypus MO Unit with about 100
Cartridges (40+ never used, all Rewritable) and was thinking of backing up
my older files (Amiga , 68K Mac etc) to this media. The hard case seems like
it would take care of one major media killer (scratches).
Jerome Fine replies:
I have a Sony SMO S-501 drive, actually several,
along with more than 200 media. I have never had
a problem with the media, but I did have to replace
both drives about 5 years ago on a system which was
first installed in 1990 and had frequent usage.
My advice would be to make at least 2 copies of the
media for important files and 3 copies for critical
data. But you should also have more than one drive
if you expect to be able to read the files at some
future date. Even a second host adapter (I assume
this is a SCSI device) would not be unreasonable,
especially for a PC system which is not too expensive.
For a PDP-11 Qbus system, the host adapter can be
around $ 500 or so, but in this case having more than
one might also be essential if reading the data when
it needs to be read is critical as well.
I all depends on how important it is to be able to
read the data in the future. In the long run, you
might also consider making a copy of the MO media
to a DVD which would provide an additional level
of security to the backup. This might actually
be very easy to perform if you use an emulator
which can read the raw SCSI blocks and copy them
from / to a file on a hard drive which can then
easily be copied from / to the DVD for backup.
I do this now all the time with files which were
originally on the MO media, the MO media itself
being a backup of files which were on an ESDI
hard drive on the PDP-11. Originally, the MO
media was used as the backup to the ESDI hard
drive and was able to re-create the hard drive.
On a PC, I created a file the size of the ESDI
hard drive (about 600 MBytes) and copied the MO
media contents to the file on the PC. After
about 5 years when I acquired access to a DVD
burner, it was natural to also backup those files
on the hard drive to a DVD. Since I no longer
do much actual work on the real PDP-11, work
is now mostly on the PC (where I run RT-11 under
an emulator) and files have a backup on a DVD.
BUT, if I even need a large volume of data
transferred back to the PDP-11, the MO media
will be used to perform the transfer - another
invaluable use for the MO media.
Sincerely yours,
Jerome Fine
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