22 Oct
2007
22 Oct
'07
12:12 p.m.
Al Kossow wrote:
Yep, went
through that at the museum because some people were
advocating
putting media on the archive shelves - but
it's not an idea I'm a
fan off; the
stuff's just too prone to damage and decay.
Unless you recover the data, what you have is a physical artifact of a
magnetic
storage medium. There is absolutely no way to say what, in fact, is
even on it
until you read it. Bits aren't preserved if they exist on only one
physical medium,
which you may not be able to recover in the future. from 2002 through 2005. My current system has used a
C:
drive with approximately 2 GB of files for about the past
5 years. GHOST compresses that to an image file of just
under 1 GB which allows me to fit 4 images per DVD or 3 DVDs
per year with one image saved each month.
About once a year, I take a whole day and read all of the old
files back to the hard drive and check for a valid file by
producing and comparing the current MD5 value with the original
MD5 value. Thus far this exercise turned up only one bad file
which could not be read back - at the extreme edge of the DVD -
which had a clear fingerprint at the edge of the DVD media.
I am considering making up a DVD with all of the December 31st
images since after 4 years, over 50 different end of month images
hardly seem very important any more.
In addition, I have all of the RT-11 binary distributions on
a CD and a second CD with the DECUS RT-11 CD from Tim Shoppa.
Every so often, I also read these media as well. The ISO files
from both CDs are on a DVD with other RT-11 archived
files.
Since the CD is over 20 years old and still supported on current
DVD burners, I suspect that the single layer DVD will also be
around for at least another 10 years. At that point, an upgrade
to the current media type may be needed. Since I have used the
following as backup media over the past 30 years, it will not be
unexpected:
RX02 - 1/2 MB (around 1980)
TK25 - 32 MB (around 1985)
TK70 - 256 MB (around 1990)
5 1/4" optical Sony SMO S-501 compatible - 290 MB on each side (around 1995)
CD - 600 MB (around 1995)
DVD - 4 GB (around 2002)
Sincerely yours,
Jerome Fine
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