[log in to unmask] wrote:
> On January 22, 2004 9:57 PM, Konrad Strauss wrote:
> > Of course these drives were spinning and subject to stress which caused
> > their failure. If the drives were in storage they would not have been
> > subjected to stress.
> On the AES/ ISO Joint Technical Commission on Magnetic Media Stability, we
> have recently been talking to the manufacturers of HDD's.  From what we have
> been able to learn, all longevity/stability testing that has been done has
> been while the drives were spinning.  The manufacturers have not done any
> testing and have no collected data on the what happens to the drives if they
> are inactive and sitting on a shelf.
> One might keep in mind the published papers on magnetic tape where the
> manufacturers produced testing that "proved" some tapes could survive
> thousands of passes before showing significant degradation in signal
> reproduction. Of course, this testing occurred in controlled laboratory
> conditions and the tapes were simply shuttled back and forth on a single
> carefully aligned and maintained machine.  The tests implied longevity for
> the tapes but it doesn't work this way in the real world.
> I would be hesitant to assume that HDD's are safe to store for long periods
> on the shelf without some significant testing of HDD's that have been
> exposed to various conditions while not in the spin mode.
> Peter Brothers
> President
> (201) 440-6589
> Celebrating 20 Years of Restoration and Disaster Recovery Service

While testing 4 mm and 8 mm helical scan tapes some years ago, we
conducted pseudo-wear tests that consisted of multiple passes. The area
within each pass remained satisfactory, but residue accumulated at each
end of the wear region. This residue caused drop-outs and read errors,
and consisted of particles from the magnetic coating itself. Such tapes
had significant problems if the recording area was subsequently expanded
outside of the wear test region.

Work with both tape and floppies has shown that such particles bind very
strongly to like material that constitutes the recording surface, and
are quite difficult to remove. This binding is enhanced while the tape
layers are stored under tension. Their presence causes media-head
separation during recording and playback that results in errors.

Spacing between the head and media is one of several advantages of
non-contact optical storage.

Media Sciences, Inc.