Selective Head Imagers and Head Fly-Height

[Cris]

Hello Experts

I have been researching hardware imagers that are capable of selective head imaging, and was just wondering a few things.

1. I believe some hard drives have adjustable head fly-height; is this a feature on most modern drives?

2. When a head is disabled (and it has adjustable fly-height), is its fly-height increased to maximum height to reduce likelihood of crashing?

Thanks in advance.

Cris

[loki]

Hello Experts

I have been researching hardware imagers that are capable of selective head imaging, and was just wondering a few things.

1. I believe some hard drives have adjustable head fly-height; is this a feature on most modern drives?

2. When a head is disabled (and it has adjustable fly-height), is its fly-height increased to maximum height to reduce likelihood of crashing?

Thanks in advance.

Cris

Interesting? Not heard of adjustable head fly height?
When the platters spin an air bearing is created that lifts the head just above the platters.


Loki

[hddguy]

Flight height is determined by Preamplifier, I am not sure that there are any imagers that can control this, I do not know of one.

[loki]

Flight height is determined by Preamplifier, I am not sure that there are any imagers that can control this, I do not know of one.

I assume the that preamp somehow measures the rpm & if thats in tolerance then in theory the heads will be at the correct height due to the air bearing that is created.

[Cris]

I was reading about Thermal Fly-height Control (TFC) Technology in Hitachi Hard Disk Drives:

http://www.hitachigst.com/tech/techlib. ... 041807.pdf

and thought maybe it was a common thing.

The real reason for asking is I was wondering why some of the literature implies it is safer to image with the good heads first, and then try with the faulty heads last. I first though it was because the faulty heads were at greater risk of crashing, but now I presume it is safer because it leaves the most strain intensive part of the imaging until last. Is that correct?

[Cris]

Has anyone ever tried running hard drives in different gas densities and monitoring: S.M.A.R.T. Attribute: Flying Height?

[Doomer]

flying height is controlled by drive and it can be different for reading, writing and for each head in each zone
These parameters are written in adaptives, so drive does not increase flying height if head is disabled unless adaptives modified accordingly

[labtech]

I was reading about Thermal Fly-height Control (TFC) Technology in Hitachi Hard Disk Drives:

http://www.hitachigst.com/tech/techlib. ... 041807.pdf

and thought maybe it was a common thing.

The real reason for asking is I was wondering why some of the literature implies it is safer to image with the good heads first, and then try with the faulty heads last. I first though it was because the faulty heads were at greater risk of crashing, but now I presume it is safer because it leaves the most strain intensive part of the imaging until last. Is that correct?

Yes

[fzabkar]

flying height is controlled by drive and it can be different for reading, writing and for each head in each zone
These parameters are written in adaptives, so drive does not increase flying height if head is disabled unless adaptives modified accordingly

Is it actually possible to increase the flying height?

IIUC, there is a heating coil that swells the slider in order to reduce the flying height. If you remove power from this heater, as would presumably be the case when this head was not reading or writing, then wouldn't the head just fly at its maximum height as determined by the air bearing?

[Cris]

If you remove power from this heater, as would presumably be the case when this head was not reading or writing, then wouldn't the head just fly at its maximum height as determined by the air bearing?

That is what I was thinking.