new ssd

On 12/8/2012 5:12 AM, RayLopez99 wrote:
On Saturday, December 8, 2012 6:42:31 AM UTC+2, Paul wrote:

hard drives. Bad design ideas (400 spindowns per day)

still plague some products. But many aspects of

hard drives, are nothing short of amazing.


Yes, they use for example 'ground effect' to control how close the
head is to the spinning platter. That's why the oft-cited stat that
running a HD is "like flying a Boeing 747 six inches above ground" is
a bit dishonest--you need to be close to the ground to get a smooth
boundary layer, no turbulence, let air laminar flow keep your heads
close automatically type situation.

RL



A LONG time ago we (at work) had some real HARD drives, the platter was
spun by a 1/3hp capacitor start 110v electric motor. there was also a
60psi air compressor that was used to provide air pressure to force the
FIXED heads, 10 per side of the platter, down to the platter surface so
the read/write would work. The platter was somewhere in the range of 20"
across. would take 2 techs to change one or a really strong tech to
horse one around by himself. The forced air was used to overcome the
laminar air flow of the spinning disk which wanted to push the heads
away from the platter.

On Saturday, December 22, 2012 7:48:21 PM UTC+2, hp wrote:

A LONG time ago we (at work) had some real HARD drives, the platter was

spun by a 1/3hp capacitor start 110v electric motor. there was also a

60psi air compressor that was used to provide air pressure to force the

FIXED heads, 10 per side of the platter, down to the platter surface so

the read/write would work. The platter was somewhere in the range of 20"

across. would take 2 techs to change one or a really strong tech to

horse one around by himself. The forced air was used to overcome the

laminar air flow of the spinning disk which wanted to push the heads

away from the platter.

Wow. Call that the "anti-ground effect" then!

20" platters?! Any further back than that and you'd be talking about sound waves traveling back and forth in a mercury tube to record data.

RL

On Sat, 22 Dec 2012 12:48:21 -0500, hp wrote:

On 12/8/2012 5:12 AM, RayLopez99 wrote:
On Saturday, December 8, 2012 6:42:31 AM UTC+2, Paul wrote:

hard drives. Bad design ideas (400 spindowns per day)

still plague some products. But many aspects of

hard drives, are nothing short of amazing.


Yes, they use for example 'ground effect' to control how close the head
is to the spinning platter. That's why the oft-cited stat that running
a HD is "like flying a Boeing 747 six inches above ground" is a bit
dishonest--you need to be close to the ground to get a smooth boundary
layer, no turbulence, let air laminar flow keep your heads close
automatically type situation.

RL



A LONG time ago we (at work) had some real HARD drives, the platter was
spun by a 1/3hp capacitor start 110v electric motor. there was also a
60psi air compressor that was used to provide air pressure to force the
FIXED heads, 10 per side of the platter, down to the platter surface so
the read/write would work. The platter was somewhere in the range of 20"
across. would take 2 techs to change one or a really strong tech to
horse one around by himself. The forced air was used to overcome the
laminar air flow of the spinning disk which wanted to push the heads
away from the platter.

You're probably thinking of something like this:

http://hpmuseum.net/display_item.php?hw=275

I had one of these in a test set years ago. The shop people were
supposed to clean the air filter once a week, and one week they forgot.
Then they called me and said the computer was making a 'funny noise'.
When I asked them to hold the phone up to it, all I could hear was the
sound of the heads bouncing off the platter... a strange high pitched
ringing. When the HP tech disassembled the drive, we could not find the
heads at all.. they had been ground into powder. I asked the tech if I
could keep the damaged fixed platter, and, 27 years later, it's hanging
on my wall. Interesting piece of hardware. The carriage that moved the
heads back and forth weighed about 20 pounds, and had a huge voice coil
electromagnet to move it. As I recall, there was a fail-safe circuit in
the drive that discharged a large capacitor into the carriage drive coil
in case the AC power failed, which would force the carriage back into the
resting position to get the heads away from the platter surface if the
airflow stopped.