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Hard disk platters all the same? Anatomy??

Found a broken HDD of 1 Tb today. Always good to take apart for the magnets. The platters were 'slightly' warped; must have been thrown around... The highly reflective platters can always be looped on a string, to chase away crows from my garden.  By now, I have several dozens of old platters.  I was thinking, apart from practicalities like dust and gentle handling, could it be possible to just substitute the platters with  other (old= much lower capacity) platters?  The 1 Tb mechanism, including the heads, would want to format the platters for a Tb amount of storage I assume. If the platters are mechanically identical (I notice they don't have a standard thickness), could this work?  Does anyone know what alloys are used, are they coated, with what??? I see no attraction when I hold a supermagnet to it, but there ought to be some kind of magnetic carrier on it.... The shine on the platters might suggest some exotic metal coating; palladium or something like that....???

jeff-o6 years ago
Hmmm, if they fit together and are the same thickness, I suppose you could combine a few together to make a working hard drive. You'd be limited by two things, the data density of the "smallest" platter, and the hardware driving the whole thing.

That is, you would not be able to write a higher density to a platter than it is capable of, and the hardware could not write a higher density than it was designed for.
BobS (author)  jeff-o6 years ago
I assume the hardware minus the old platters would try to format new platters according to the same specs. Next time I run into an old HDD I will try replacing the platters and see if it will run! (Guess a steamy shower is the best cleanroom for an amateur?)
orksecurity6 years ago
Drive capacity is not set just by the platters. They do affect things -- the materials can differ, depending on the size of the magnetic domain being recorded on them and the exact details of how it's being recorded -- but the drive's head is also different to allow the denser recording, and the electronics are different to drive that head and to record at the higher frequency.

If you websearch "how does a hard disk work", you'll find many descriptions at varying levels of detail. Beyond a certain point, of course, you start getting into the manufacturer's trade secrets... but most of this is patented and thus is public knowledge.