Hi there

Was doing some dead drive autopsying on a:

Seagate Barricuda 2000GB
ST2000DM001
9YN164-302

Had a massive amount of trails, and stiction marks on every platter, for the first time i got to try out my new microscope on some stiction marks, then i noticed something freaky.

The stiction mark appeared to be a series or tiny circles at max (90X) zoom.

Circles? Why circles? Can anyone explain this strange phenomena to me?

This drive uses patterned media (aka BPM).

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Fascinating! So each circle is a bit.

https://en.wikipedia.org/wiki/Patterned_media

http://www.toshiba.co.jp/rdc/rd/fields/11_e09_e.htm

Thanks for the input. If anyone else is wondering what microscope i used, it was an Amscope:

http://www.amscope.com/microscopes/3-5x ... amera.html

And this pattern on the posted picture is not a stiction mark.

Enlighten me. What do we call it?

I would have thought an individual bit would be a LOT smaller than this.. but I have no experience, research or knowledge to actually back this up. I notice on the link you posted they used a SEM to see the bits.

I also imagined they would be a lot smaller, strange they showed up on only 90x zoom.

After fiddling around with the scopes software i was able to get pixel measurements, at max (90x) zoom.

1mm at MAX zoom = ~750px

1 circle at MAX zoom = ~23px

23 / 750 * 100 = ~0.0306mm
or ~30.66 μm (micrometers)
or ~30666.6 nm (nanometres)

So yes these circles are about 3,000 times larger than the '10nm' quoted from that toshiba link. (If my math isn't off.)

Basically duplicating my PM to CleanestRoom here, but anyway:

Yes, these dots aren't magnetic grain for sure.
I probably should sleep more, but I asked CleanestRoom about the microscope as I thought he got his hands on some sexy equipment and decided to (ab)use it properly :)

This is an amateur judgement, but I believe optical microscopes can't produce such a detailed picture of the grain on a modern platter due to their diffractional limit.

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• Remote RAID, NAS, SAN, VMware, DVR (CCTV), flash and tape recovery. Data recovery support.

even with digital camera connected to it ?


details from the link above:

Using just the measurable parameters (max transfer rate, outside diameter, RPM), we can arrive at an upper limit for the size of a "bit".

(210 MB/s) / (7200 per minute) / (3.5 inch x pi) = 50 bits per um = 20 nm per bit

http://www.google.com/search?q=210+MB%2 ... its+per+um

Obviously the size would be lower if we were to account for the "overhead" bits.

According to the product manual (http://www.seagate.com/staticfiles/supp ... 686584.pdf), the maximum recording density is 1807kFCI (kilo flux changes per inch).

That works out to 13.6 nm per flux change.

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Software only measures pixels, there's no electronic reading of the scopes zoom so calculations must be done manually as I've done.

Hypothetical. I'm a billionaire, and i want a SEM that can read to less than 10nm, how much might that cost?

http://www.technicalsalessolutions.com/items.php?CID=3

There is one here for 8 grand...
http://www.labx.com/item/hitachi-s-2400-scanning-electron-microscope/624867

of course I haven't looked at specs, but it would do me

not insanely expensive, some bigger DR labs could probably afford one