What wears out in an HDD?
 

What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break??? Good watches use
jewels, rubies, as bearings; and cheap watches use metal. What do
hard drives use?

I googled but couldn't find much about this. Does the spindle really
ride on an air cushion? Even when the drive is positioned sideways?

What wears out in an HDD?
 

On 1/14/2016 6:44 PM, Micky wrote:
What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break???

Google once conducted a study on exactly your topic:

https://www.google.com.hk/search?q=g...KIfo0ASR6pioAg

And you can also read about RMA statistics from hard disk manufacturers:

https://www.google.com.hk/search?q=h...88.Mt994qa8-tI

Good watches use jewels, rubies, as bearings; and cheap watches
use metal. What do hard drives use?

IBM once made a hard disk with glass platters. The result was disastrous.

I googled but couldn't find much about this. Does the spindle really
ride on an air cushion? Even when the drive is positioned sideways?

Modern hard disks are very very reliable!

--
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What wears out in an HDD?
 

On Thu, 14 Jan 2016 05:44:50 -0500, Micky wrote:
What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break??? Good watches use
jewels, rubies, as bearings; and cheap watches use metal. What do
hard drives use?

Most of the causes is due to combination of heat and force.

IMO, the arm and bearings and are pretty solid but it's not impossible for
them to break - depending on the material and manufacturing quality.

https://en.wikipedia.org/wiki/Bearing_(mechanical)#Service_life

Does the spindle really ride on an air cushion?

From where did you have that thought?

What wears out in an HDD?
 

On Thu, 14 Jan 2016 22:01:18 +0800, Mr. Man-wai Chang wrote:

Modern hard disks are very very reliable!

No. Not really. Not all of them. It depends on the HDD manufacturing. Some
models are durable, and some are not.

My 160GB WD only lasted about a year while my 3 years old 40GB Seagate is
still fine.

FYI, my environment is somewhat harsh. No air conditioning (because it's in
an open room), and the air is not clean enough.

What wears out in an HDD?
 

On 1/14/2016 10:24 PM, JJ wrote:
No. Not really. Not all of them. It depends on the HDD manufacturing. Some
models are durable, and some are not.

My 160GB WD only lasted about a year while my 3 years old 40GB Seagate is
still fine.

I have never had a dead hard disk, except that IBM Deathstar that used
glass platters. The other one I lost was a Seagate ST-251 40M (yes, 40M)
which was dropped accidentally. :)

FYI, my environment is somewhat harsh. No air conditioning (because it's in
an open room), and the air is not clean enough.

Outside air shouldn't be able to reach inside the hard disk, but the
circuit board might be affected.

--
@~@ Remain silent. Nothing from soldiers and magicians is real!
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora release 23) Linux 4.3.3-300.fc23.x86_64
^ ^ 22:45:01 up 2:51 0 users load average: 0.00 0.01 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa

What wears out in an HDD?
 

On 1/14/2016 5:44 AM, Micky wrote:
What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break??? Good watches use
jewels, rubies, as bearings; and cheap watches use metal. What do
hard drives use?

I googled but couldn't find much about this. Does the spindle really
ride on an air cushion? Even when the drive is positioned sideways?


The heads ride on an air cushion, not the spindle. Any modern drive will
have an automatic unload system which causes the head actuator to retract
when the drive is powered down and the head arms are rested in a
'comb'-like rack right next to the edge of the platter. After the platter
spins up to speed the actuator moves the head arms off the rack and eases
them over the edge of the platters where the heads ride on a thin film of
air which spins along with the ultra-smooth platters thanks to miniscule
air foil shapes adjacent to the heads. There should never be any contact
and, thanks to the miniscule size of the heads in modern drives, any
contact will be disastrous.

In primitive drives the heads actually stayed over the platters and came
into contact when the drive spun down (anybody else remember the 'stiction'
problem in 10 and 20mb drives?) but the heads there were pretty beefy and
could stand a bit of rough treatment.

What wears out in an HDD?
 

Mr. Man-wai Chang wrote:
On 1/14/2016 10:24 PM, JJ wrote:
No. Not really. Not all of them. It depends on the HDD manufacturing.
Some
models are durable, and some are not.

My 160GB WD only lasted about a year while my 3 years old 40GB Seagate is
still fine.

I have never had a dead hard disk, except that IBM Deathstar that used
glass platters. The other one I lost was a Seagate ST-251 40M (yes, 40M)
which was dropped accidentally. :)

FYI, my environment is somewhat harsh. No air conditioning (because
it's in
an open room), and the air is not clean enough.

Outside air shouldn't be able to reach inside the hard disk, but the
circuit board might be affected.


Outside air *does* reach the platter. There is a hole
in the cover, with a hepafilter fastened by adhesive,
on the inside surface.

http://www.howtogeek.com/127433/what...n-hard-drives/

This is a datasheet for a filter disc for the HDA cover.
Just to illustrate they do exist.

https://www.donaldson.com/en/diskdri...ary/051290.pdf

*******

The only drives currently which are completely
sealed, are the Hitachi helium drives. (I don't know
if anyone else makes a helium drive yet or not. There
isn't a lot of helium to be wasted any more. The price
is getting quite high.)

Such a drive, wants to keep the helium inside.
(No need for a breather hole :-) )
I consider such a design to be truly miraculous,
as you know how hard it is to keep helium
gas in anything. Helium gas is used specifically
for lab testing, for the detection and removal
of leaks in vacuum systems. It's a bitch to
keep it from leaking.

Paul

What wears out in an HDD?
 

On 1/14/2016 4:44 AM, Micky wrote:
What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break??? Good watches use
jewels, rubies, as bearings; and cheap watches use metal. What do
hard drives use?

I googled but couldn't find much about this. Does the spindle really
ride on an air cushion? Even when the drive is positioned sideways?

Not exactly what you are asking but here is a blog entry on hard drive life in a very harsh environment:
https://www.backblaze.com/blog/hard-...ility-q3-2015/

Lynn

What wears out in an HDD?
 

JJ wrote:
On Thu, 14 Jan 2016 05:44:50 -0500, Micky wrote:
What wears out in an HDD? Is it only the tone arm that breaks? or
can the bearings the platter rides on break??? Good watches use
jewels, rubies, as bearings; and cheap watches use metal. What do
hard drives use?

Most of the causes is due to combination of heat and force.

IMO, the arm and bearings and are pretty solid but it's not impossible for
them to break - depending on the material and manufacturing quality.

https://en.wikipedia.org/wiki/Bearing_(mechanical)#Service_life

Does the spindle really ride on an air cushion?

From where did you have that thought?

The spindle rides on a fluid cushion. Look for
information on FDB (fluid dynamic bearing) motors.

http://www.madshrimps.be/files/image...frey-21203.jpg

https://www.hgst.com/sites/default/f...aper_FINAL.pdf

FDB motors are available, where the shaft is fixed
on one end, or fixed on both ends. (Most of the
diagrams for these things are crap, and impossible
to figure out from the picture.)

FDB motors control NRRO (non-repeatable runout or "jiggling" :-) ).
Without the reduction in runout on modern FDB motors
(versus those using ball bearings), you could not have
your 4TB hard drive.

*******

The *head* floats on a cushion of air. And it's not really
a cushion shape either. There is a fairly small, fairly high
pressure zone near the head, that prevents contact (most
of the time).

The drive even has the ability to measure what that height
is, using "tricks" related to the signal sent to the head.
Some drives are able to detect a too-high flying height
on a write operation, and redo it. I don't have any data
on what percentage of drives have this capability. Drives
vary, in how many other drives they can tolerate
nearby, all jiggling at close to the same frequency.
Some "bargain" drives, might only be happy if they are
by themselves. Others are server rated, living in racks
with a lot of other drives.

*******

The mystery bearing in a hard drive, is the bearing
for the arm. Obviously, it needs to meet a decent
spec, due to flying height as the arm moves
from one part of the disk to another. And the
bearing could be quite conventional for all I know.
There's no "pumping action" to make an FDB there.

What you should be impressed with, is the cable that
makes the electrical connection from the arm, to the
PCB. That goes through millions and millions of
bending cycles. The engineering inside hard drives
is nothing short of amazing. Especially given the
low price of the bottom-end drives. Cheap and precise,
all in one modest package.

Paul

What wears out in an HDD?
 

On Thu, 14 Jan 2016 13:11:40 -0500, Paul wrote:



The only drives currently which are completely
sealed, are the Hitachi helium drives. (I don't know
if anyone else makes a helium drive yet or not. There
isn't a lot of helium to be wasted any more. The price
is getting quite high.)

Where I live, a dollar store sells helium baloons for a dollar.

I see people buy 5 at a time. It's terrible and such a waste. You
can learn all you need to know from one balloon.

There should be a 3000% excise tax on helium.