🚀 go-pugleaf

In article <1993Jan5.193232.1930@cbnewsm.cb.att.com> evans1@cbnewsm.cb.att.com (Dan Evans) writes:
>In article <1993Jan5.001013.15268@engage.pko.dec.com> ssmith@ncdel.enet.dec.com (Sheldon E. Smith) writes:
>>
>>From this and other things said, can I use (cheaper) 3 1/2 DD disks in my HD
>>drive without problems?   Assuming I ADD THE SECOND HOLE?
>>
>
>As long as they format to the full 1.44 MB I don't see why not. But you
>wouldn't catch me doing that for a hard drive backup. I may just be paranoid.
...

The failure mode for DD disks used as HD is quite insidious.  The
recorded data will tend to decay slowly.  Weeks or months later, you
may find that your data has become unreadable.  The average "half life"
for the data has been reported to be approximately six months [Mueller,
"Upgrading and Repairing PCs," 2nd edition, Que, 1992, p.546].

Contrary to what the vendors of hole punchers say, the media are *not*
the same.  You can confirm this by the simple experiment of opening the
shutter on a HD disk and looking through it at a light source.  Now,
try that with a DD disk.  The magnetic coating on DD disks is both
thicker and magnetically "softer."  The latter characterictic is what
causes the closely-packed bits to merge into a useless jumble over time.

Also, in my experience DD disks will seldom format to a full 1.44MB.
The inner cylinders (where the bits are most tightly packed) almost
invariably have several bad sectors -- a pretty solid indication that
the media is being pushed beyond its limit.

With bulk HD disks available for $0.60 to $0.80 each, it's just not
worth it to fool around with DD, IMO.

Bob Nichols
AT&T Bell Laboratories
rnichols@ihlpm.ih.att.com