hard drive park position

[somae7/newsguy]

I recently took apart a maxtor hard drive.

I was wondering if the hard drive head should be in the center or edge of
the disk when in the park position?

Thanks.

 

[John Doe]

I recently took apart a maxtor hard drive.

I was wondering if the hard drive head should be in the center
or edge of the disk when in the park position?

I would ask in the storage group.

 

[VanguardLH]

I recently took apart a maxtor hard drive.

I was wondering if the hard drive head should be in the center or edge of
the disk when in the park position?

Thanks.

From my readings, for current hard disks the head parking is automatic
when power is removed. Although the logic of the PCB on the hard disk
may accept a Park command, it is not an active process that is honored.
The head actuators have springs to position them when power is removed.
When there is power, the actuators move against the spring tension.
When power is cut, the actuators automatically retract.

While I saw the above comments in several articles, here is one example
of them:

http://www.brainbell.com/tutors/A+/Hardware/_Actuator_Arms.htm

Because of the springs, the heads are self-parking when power is
removed. So unless the actuator assembly is damaged to prevent its
return to the parking position on power down, you should be seeing where
the heads are to park when you opened the case.

http://www.pcguide.com/ref/hdd/op/act_Actuator.htm
http://www.storagereview.com/guide/actActuator.html
"The first PC hard disks in 1982 had a track density of only two or
three hundred tracks per inch (TPI). Even In 1986, the year Conner
Peripherals introduced the first voice coil PC hard disk, density had
increased to only about 1,000 TPI."

So voice coil actuators were introduced back in 1986. I don't know how
fast they proliferated into the market to become the pervasive
technology. My original guess is that stepper motors disappeared over
15 years ago but apparently it begun before that.

Hard drives have been self-parking for a long time now. All you have to
do when moving the drive is power it down. You don't need to issue a
parking command. Where the actuators come to rest when powered down due
to spring tension is the parking position (barring physical damage).

 

[Franc Zabkar]

I recently took apart a maxtor hard drive.

I was wondering if the hard drive head should be in the center or edge of
the disk when in the park position?

Thanks.

Most (all?) modern hard drives now park their heads off the platters
on a loading ramp. One reason is to prevent stiction.

See the following Hitachi whitepaper.

Ramp Load/Unload Technology in Hard Disk Drives:
http://www.hitachigst.com/tech/tech...5825FB/$file/LoadUnload_white_paper_FINAL.pdf

Earlier designs parked the heads on the outer edge of the platters.

- Franc Zabkar

 

[somae7/newsguy]

Most (all?) modern hard drives now park their heads off the platters
on a loading ramp. One reason is to prevent stiction.

See the following Hitachi whitepaper.

Ramp Load/Unload Technology in Hard Disk Drives:
http://www.hitachigst.com/tech/techlib.nsf/techdocs/9076679E3EE4003E86256FAB
005825FB/$file/LoadUnload_white_paper_FINAL.pdf

Earlier designs parked the heads on the outer edge of the platters.

- Franc Zabkar

The reason I was asking is because it seems the head got stuck. According to
something I read, if you get a clicking sound from the drive, it could be an
indication that the head didn't park properly.

I was getting a clicking sound and the head seemed to be stuck in the middle
of the platter. I was able to move it to the edge but destroyed the drive in
finding out how to open it.

I have another one that I want to try and restore, that has the same
problem.

 

[John Doe]

I was able to move it to the edge but destroyed the drive in
finding out how to open it.

That answers the question I was afraid to ask.

How to open it does not matter, opening a hard drive destroys it.

Again... You cannot open a hard drive outside of a clean room without
destroying it.

 

[Guest]

I recently took apart a maxtor hard drive.

I was wondering if the hard drive head should be in the center or edge of
the disk when in the park position?

All hard drives made since about 1990 automatically park their heads
when power is turned off, the older ones by moving the heads toward
the center of the platters, to an area not used for data, the newer
ones by moving the heads beyond the outer edges of the disks, usually
by sliding the head arms onto nylon ramps. The latter has the
advantages of keeping the heads from hitting anything when parked and
preventing the heads from sticking to the platters and preventing the
drive from spinning when power is turned on. Head sticking was a
major problem with Seagate drives made in the late 1980s because the
platters were manufactured with too much protective lubricant, which
would pile up on the head sliders, and Seagate and other companies
tried to prevent sticking by roughening the parking area with acid or
laser burns. The power for moving the heads to the park position is
generated from the inertia of the spindle motor as it coasts to a
stop; only a very few designs used a spring to retract the heads.

 

[Guest]

The head actuators have springs to position them when power is removed.
When there is power, the actuators move against the spring tension.
When power is cut, the actuators automatically retract.

While I saw the above comments in several articles, here is one example
of them:

http://www.brainbell.com/tutors/A+/Hardware/_Actuator_Arms.htm

Because of the springs, the heads are self-parking when power is
removed.

That web page is full of misinformation. Very few self-parking hard
drive designs have used springs to park the heads, and it's been far,
far more common for the spindle motor to be turned into a generator,
just when the power is disconnected, to provide electricity for moving
the heads to the parking area. Even many designs employing stepper
motor head positioners used that method, and some models, like the
5.25" Seagate ST-251/ST-277R, would buzz rather loudly during the
process..