5k1000 - 7k1000

[ddd123]

Hi
Can anybody share experience if the heads
between 5k1000-1000 and 7k1000-1000 are compatible?

thanks

[digisupport]

Compatible

[fzabkar]

I would have thought that the aerodynamic design of the heads and the RPM would determine the fly height. So how can a head designed to fly at 7200 RPM work in a 5400 RPM application? Wouldn't it fly lower?

[BGman]

5k1000-1000 are drives that did not pass tests for 7k1000-1000. They just put new FW and run tests for 5k1000-1000.

[pcimage]

Compatible

Yep, done it many times

[larrymoencurly]

So how can a head designed to fly at 7200 RPM work in a 5400 RPM application? Wouldn't it fly lower?

Hitachi once advertised CoolSpin for 7200 RPM drives, maybe the 7K1000.c or 7K3000, that could reduce the speed to something like 4500 RPM during idle periods, but it had to be enabled through Drive Fitness Test.

[fzabkar]

So how can a head designed to fly at 7200 RPM work in a 5400 RPM application? Wouldn't it fly lower?

Hitachi once advertised CoolSpin for 7200 RPM drives, maybe the 7K1000.c or 7K3000, that could reduce the speed to something like 4500 RPM during idle periods, but it had to be enabled through Drive Fitness Test.

You will probably find that the the heads are retracted onto the loading ramp during this time, not flying over the platters.

[fzabkar]

It's called "low power idle mode".

Attachments

[sin]

red bull gives you wings

--
PS interesting post

[BGman]

I would have thought that the aerodynamic design of the heads and the RPM would determine the fly height. So how can a head designed to fly at 7200 RPM work in a 5400 RPM application? Wouldn't it fly lower?

The newer HDD's use a piezocrystal to control the fly height...

[fzabkar]

I would have thought that the aerodynamic design of the heads and the RPM would determine the fly height. So how can a head designed to fly at 7200 RPM work in a 5400 RPM application? Wouldn't it fly lower?

The newer HDD's use a piezocrystal to control the fly height...

As I understand it, that piezo crystal controls fine servo position. Are you referring to some other crystal?

Here is WD’s / HGST’s white paper on microactuators:

Second-generation Micro Actuator for Better Head-positioning Accuracy:
https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/tech-brief/tech-brief-western-digital-micro-actuator.pdf

Seagate refers to theirs as AcuTrac:
https://www.seagate.com/files/staticfiles/docs/pdf/whitepaper/seagate-acutrac-TP624.1-1110US.pdf

Thermal fly height control is described in this Hitachi paper:
https://web.archive.org/web/20101213153652/http://www.hgst.com/tech/techlib.nsf/techdocs/98EE13311A54CAC886257171005E0F16/$file/TFC_whitepaper041807.pdf

[Doomer]

I would have thought that the aerodynamic design of the heads and the RPM would determine the fly height.

RPM does not determine the fly height and aerodynamic design is the same for sliders of the same generation and manufacturer.
It's common for Hitachi drives to have interchangeable heads between 5K and 7K models, not only between 5k1000 and 7k1000

[pepe]

... and FH is controlled by a heater element. or two.

pepe