Why do they take at least 10% off a HDD?

12
Posted 10th Jan
Recently ordered a 4TB westerndigital hard drive from a deal posted.

Seems to be working fine, but my question is it’s 4TB, why the hell does it have 3.63TB capacity left? Where the hell has the other 370GB gone?

I understand some may go to the software of the drive, but 370GB?
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The computer measures 1 TB as 1024 GB and 1 GB as 1024 MB, but manufacturers state 1 TB is 1000 GB and 1 GB is 1000 MB, so you seem to lose a fair amount when the computer reads the drive.
Edited by: "RandomUser42" 10th Jan
It's the difference between decimal and binary, the "missing" space never existed.
Pc hardware manufacturers cheating you (by using different units) basically

Hard drive and SSD manufacturers use the gigabyte to mean 1000000000 bytes. Therefore, the capacity of a 128 GB SSD is 128000000000 bytes. Expressed in gibibytes this is about 119.2 GiB. Some operating systems, including Microsoft Windows, display such a drive capacity as 119 GB, using the SI prefix G with the binary meaning. No space is missing: the size is simply being expressed in a different unit, even though the same prefix (G) is used in both cases.

en.wikipedia.org/wik…yte
Edited by: "MadeDixonsCry" 10th Jan
It's all FAT and that
Edited by: "ra786" 10th Jan
Various units in computing are either expressed using powers of two or powers of ten. Most fields have agreed on one or another - for example RAM is always powers of two, while networking is always powers of ten.

For some reason storage never settled, with manufacturers and software developers both deciding to stick to their preference.
MadeDixonsCry10/01/2020 18:57

Expressed in gibibytes


Gibi-bytes and so on were invented prefixes that came about later in attempt to broker peace, but they had such silly names nobody's ever taken them seriously.
Edited by: "EndlessWaves" 10th Jan
Don't they use Giga Octets/GO instead of GB in some countries? Which would make more sense. I think.
There's also a certain amount of disk lost through the file table allocation (FAT) or similar depending on the file system type. Different systems will use different amounts, but nowhere near the amount you're talking about.

The other thing that might make a difference is the block size, as larger blocks will make the free storage amount disappear quicker.
just the way they use standard SI units instead of 1024 for 1KB they use 1000.
You are getting your TB and TiB confused


When you buy a 4TB disk, you will get 4TB (4,000,000,000,000 bytes) of storage rather than 4TiB (4,398,046,511,104 bytes). The disk will be smaller than you expect. A disk advertised as 4TB (terabytes) will store about 3.64TiB (tebibytes)


1 kibibyte = 1024 bytes = 1KiB

1 kilobyte = 1000 bytes = 1KB
Edited by: "chocci" 11th Jan
There was even a court case in the US many years ago about it; a good explanation is available in the article. link
powerbrick11/01/2020 03:06

just the way they use standard SI units instead of 1024 for 1KB they use …just the way they use standard SI units instead of 1024 for 1KB they use 1000.


Bytes aren't an SI unit.

The prefix names are borrowed from the SI system, but it's perfectly normal to adjust borrowed words so they mean something different.

Look at biology for example. You don't expect millipedes to have 1/1000th feet, or Meglodons to have a million teeth.

chocci11/01/2020 04:57

You are getting your TB and TiB confused



When was the last time you heard someone use a chibibyte in reality? This was a proposed compromise solution that nobody liked.
EndlessWaves11/01/2020 12:01

Bytes aren't an SI unit. The prefix names are borrowed from the SI system, …Bytes aren't an SI unit. The prefix names are borrowed from the SI system, but it's perfectly normal to adjust borrowed words so they mean something different. Look at biology for example. You don't expect millipedes to have 1/1000th feet, or Meglodons to have a million teeth. When was the last time you heard someone use a chibibyte in reality? This was a proposed compromise solution that nobody liked.


cant say I have ever heard of a chibibyte
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