"Greg Simmons" wrote:
>...I believe that hard disks are all sealed and airtight...
Nope. Civilian hard drives have a breather hole.
"...The HDD's spindle system relies on air pressure inside the
enclosure to support the heads at their proper flying height while the
disk rotates. An HDD requires a certain range of air pressures in
order to operate properly. The connection to the external environment
and pressure occurs through a small hole in the enclosure (about 0.5
mm in diameter), usually with a carbon filter on the inside (the
breather filter, see below). If the air pressure is too low, then
there is not enough lift for the flying head, so the head gets too
close to the disk, and there is a risk of head crashes and data loss.
Specially manufactured sealed and pressurized disks are needed for
reliable high-altitude operation, above about 3,000 m (10,000 feet)..."
from http://en.wikipedia.org/wiki/Hard_disk
See the section on disk integrity
If you check the specifications for a device that uses a hard drive,
you'll always see a warning like this:
"Maximum operating altitude: 10000 feet (3000 m)."
Does this mean that at 10,001 feet the device will break down? No, of
course not. What it means is that the hard drive becomes increasingly
likely to fail. And when it fails, the manufacturer won't accept any
responsibility.
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