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# Hard Drive Calculations

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How is the actual sized of a hard drive figured out?

I have 4TB drives installed, but they show up as 2.73TB. Now this is not news obviously, but I am looking to upgrade and wondering how much space I would actually gain?

Looking to get some 6TB drives, but not if it equals only 3TB lol, if you know what I mean. So should it be the same as 4TB, meaning it would be 5.73TB? I remember it always being more the larger the drive size? Is that correct?

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If you are using windows, most likely it will create a restore partition. So while it is 4TB, your actual partition is smaller.

If you are using it for storage, remember the Mb to MB ratio.

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I am talking about storage. Though not RAID or anything.

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Then dismiss my first half.

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Your second half means nothing to me? lol I do not understand

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A 4TB drive is showing up as only having 2.73TB? There's something wrong there if you don't have the drive partitioned. Even if you factor in the difference between bits and bytes, you're missing space.

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Are the disks partitioned in GPT?

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Really? Its StableBits DrivePool that is a telling me that size. I have my drived pooled, and all hidden except the pooled master drive.

That being said, what should it be, and again....how is that figured, how much will a 6TB give me?

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This should help: http://www.ussscctv.com/harddrivesizecapacitiescalculator.aspx. There is a calculator at the bottom, seems approximately 7% less than the advertised space.

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2.7 would be the reported size for a 3TB drive.  A 4TB drive should be 3.7.

6TB should be around 5.4 apparently.

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As an example, I just plugged a 4TB HDD in to my machine and I'm told that it's more like 3.64TB. When I compare that with the link that Blueclub suggested, that seems more within range than 2.73TB.

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4000 - 7% = 3720

Every new hard drive you get, you take 7% from it and you get the actual size...  If your drive shows less than 3TB that's cos your 32bit OS and you are not using the GPT format like francescob mention.  To use higher than 3TB in size you need to use that format... I read that somewhere before...

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i'd say this cannot be a GPT problem, as MBR partitions are only able to address up to ~2,2 TB.

and this also has nothing to do with 32bit OS, as windows vista (or newer) in 32bit works fine with GPT partitions.

a 4 TB partition should have a capacity of ~4.000.000.000.000 bytes (usually slightly more) or 3,63 TiB.

-andy-

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I am Windows 8 64bit

And I am not sure what you mean by GPT, if that is related to UEFI and the above 2.2 partitions then yes it is. As Andy just pointed out, it would be around 2.2 where its stuck if it was.

Hmm, sry guys, I just looked and I have 3TB drives, for some reason I thought I got 4TB when I bought them. So thats correct.

Also, you have now told me how to figure out the size of 6TB, thanks :)

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