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I'm having problems using an external 3TB hard drive. I've tried using both MBR and GPT, and in both cases my computer only sees 746GB. However, I have another 3TB hard drive (also Western Digital, but not identical) which works perfectly fine in the same enclosure.

I should also point out that my computer is a bit old, and only supports 2.2TB hard drives when connected internally via SATA. However, as far as I know, this issue should not exist with USB.

So my question is, why does one hard drive work fine, and the other only shows 746GB in the same USB enclosure? It must be a difference between the hard drives, but what exactly, and how do I find an enclosure that supports "it"?

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1 Answer 1

The difference between drives is sector size: 512 bytes vs 4KB.

There is an article explaining it in Wikipedia and on Western Digital's site.

The product must be new (2011?)

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how does this cause the size difference wierdness tho? –  Journeyman Geek May 28 '12 at 2:50
It most likely is caused by binary sector count showing only a fraction of integer division by 2.2Tb. Divide 3Tb by 2.2Tb you get 1 integer count and remainder of some 7XXGb. The integer part is lost after truncation, so the OS sees only 7XXGb –  user27803 May 28 '12 at 2:56

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