questionswhy are larger hard drives so much cheaper per gb…

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Actually the irony of it is that they're usually exactly the same everything except firmware.

The same physical device is capable of being configured to present itself as multiple different capacities based on the configuration parameters specified in the software that runs on the drive electronics.

Chew on that for a while.

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You know the statement that you pay as much or more for the box as you do for the cereal inside of it? That applies here. You need all the same elements for a small HD as you do for a large, they just tweak bits and pieces. Same case, same motor, same reading head. They will charge the same for the basic parts and the R&D in every drive they build so most of the cost is fixed.

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It's more than the enclosure.
You have drive electronics and motors, etc. to contend with that are common across both drives.

@durkzilla: Don't they add platters or enable "Side 2" for increased capacity?

j5 j5
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Ah, I hadn't thought of all the other bits like motors and electronics and whatnot. Makes sense.

@durkzilla: Interesting... Does that mean it's possible to buy a smaller capacity hard drive and then change the firmware to let it hold more?

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@j5: number of used platters, read/write heads, cylinder density (the space between the tracks), bit density (the space between the bits on the tracks). Maybe they add another physical platter, but it's cheaper to set up a factory to run one model of hardware then parcel them out based on tested performance. The microprocessor industry does this too (your 2 core CPU may well be a 4 core chip that failed the 4 core QA testing).

@panthiest: Theoretically, yes. But as you may suspect, the hard drive manufacturers closely guard their firmware secrets to prevent this. Additionally, your 1 TB drive probably failed the 1.5 TB or 2 TB quality tests, so making this change on your own would most likely result in unsatisfactory results.

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The other option is to simply set the value in the firmware that the OS sees to the desired value and not change any of the actual disk operational parameters.

Conspiracy theorists on the interwebs have postulated that large systems builders do this so they can prebuild the hardware then tweak the machine to match the customer's order without having to spend money to have a drive swapped out (or 10,000 drives, for really big orders).

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@durkzilla: Damn, I was afraid you might say something like that. Still, they're cheap enough that I guess I can't complain too much

edit: I don't know much about how these things work, but wouldn't it cause problems when you approached the limit if you make it bigger just changing a value like that?

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@panthiest: The drives are sold by the manufacturer rated for the maximum capacity. The system builder chooses to include that drive in all the machines, but mark them as smaller drives so they don't have to pay to swap the drives or stock the various parts. They pay a little more per drive, but make up the difference in reducing labor costs and the ability to ship product quickly.

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@durkzilla: ahhh gotcha. thanks for explaining all that :)

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@panthiest: Back in the 80's, a common thing to do was use RLL (or ERLL) controllers on MFM hard drives, increasing the density/capacity by 50% (90%-100%). But that was back in the days of separate controllers ... and doing the low level format yourself ... and manually setting the interleave ... and manually entering the bad sectors ... and manually parking the hard drive heads before shutting down the computer.

These days ... don't count on it at all.

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I always perceived it to be like buying paint. You can get a quart for $12 or 4 times as much for $25. I figured it was in the packaging costs.