This is the last thing I'm going to say on the subject...
On Thu, 18 Aug 2005, Peter Arremann wrote:
On Thursday 18 August 2005 22:13, Claude Jones wrote:
On Thu August 18 2005 3:18 pm, Mike McCarty wrote:
As I mentioned before, tape is very reliable. It has been shown to have
20+ year retention. One gets "wear and tear" only when the tape actually
moves. For data archival purposes, this is effectively never.
Since I've spent over thirty years in the media sector, first sound
engineering, and now television, I can't let this claim pass. You've
repeated it as gospel. I'm sure there are some studies that would make your
point, but, in real world conditions, I would never trust critical backups
to tape. Even supposing a tape's data was intact after 20 years, what would
be the state of the technology? What would you retrieve your data with?
I've dealt with every format of tape there is. Even if it's stored
properly, vertically, not horizontal on the spool, in temperature and
climate controlled conditions, there is a wide disparity in tape longevity.
BetaSP tapes that cost us $60+ when purchased new, will vary widely in
their playability even after ten years. Older 3/4" stuff is deteriorating
rapidly in our archive, and we're in a rush to transfer mode lately, to get
the material off them and on to newer media. The machines that will play
this stuff are also getting harder and harder to maintain, and find parts
for. I've encountered many horror stories about computer tape backups as
well. Meticulously done, perfectly stored, and tape drives kept up to spec,
may succeed in the 20-year life you speak of, but those conditions are
almost never met in the real world. If you have the staff to maintain the
stuff, the equipment to be maintained, the climate controlled storage
environment, along with many other factors, you might get by with tape
backup - I personally would only recommend tape as a secondary repository.
Agreed. I can't recommend tapes for anything longer than a few weeks if you
really need your data. We have all kinds of tape formats where I work and
none have ever been reliable for more than a few months.
The only viable option you have for long term is MO...
There are complex set of problems that revolve around preserving data for
long periods of time that defy simple answers. rescuing files in obsolete
formats off media formats that were no longer supported was my bread and
butter for a while. The best thing you can do is move all your data
everytime you get a new storage technology, before the hardware thta
supports it can't be connected to a modern machine, before the file format
is not longer supported, before the media you assumed worked because they
did the last time you tested them failed...
What computer media from 20 years ago (1985) can you still read? 51/4"
floppies? mfm, rll sasi, or esdi hard-disks? 9-track tape? 1/4" qic tape?
tk50? variable speed 3.5" floppies? disk pack?
how about 30 years ago? got a punch card reader? paper tape? cassette
deck? 9 track tape? 8" floppy? ibm winchester drive?
Now? does anyone here believe a significant amount of computer media will
actually rotate in 20 years?
Peter.
--
--------------------------------------------------------------------------
Joel Jaeggli Unix Consulting joelja@xxxxxxxxxxxxxxxxxxxx
GPG Key Fingerprint: 5C6E 0104 BAF0 40B0 5BD3 C38B F000 35AB B67F 56B2
