hard drives not what they say they are

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hamish225

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#112202 30-Nov-2012 03:15

So, you know how hard drives are advertised as being say, 500GB, but when you plug them into your computer they only show up as having 465GB, how is that not against the law, aren't things supposed to have exactly what they say they have and nothing less, like if i wanna buy a 500GB hard drive, i want to be able to use all 500 of those GB's

the same thing happens with my terabyte hard drive, it's not a terabyte its 931gb. a TB is 1024GB not 931.

*Insert big spe*dtest result here*

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#724979 30-Nov-2012 06:40

Hard drive manufacturers quote the capacity of their drives by the decimal system, were kilo*=1,000 (and mega*=1,000 kilo* etc), whereas operating systems usually use the ‘binary standard’, where kilo*=1024 etc. On large modern hard drives this can amount to quite a difference.

Secondly, formatting discs involves creating a filesystem – a way of organising the files and folders on the disc (a bit like having table of contents, page numbers and indexes in a book), and this uses up some space. Depending on the filesystem, the amount of space can be considerable.

1080p

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#724992 30-Nov-2012 07:44

I suggest OP read the Wikipedia articles on binary prefixes & International System of Units.

sbiddle

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#724994 30-Nov-2012 07:49

1080p: I suggest OP read the Wikipedia articles on binary prefixes & International System of Units.

sbiddle

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#724996 30-Nov-2012 07:52

hamish225:
the same thing happens with my terabyte hard drive, it's not a terabyte its 931gb. a TB is 1024GB not 931.

Incorrect.

A terabyte is 1000 gigabytes in using standard SI units or 931 gibibytes in binary.

HDD's storage is always measures in SI units. File systems typically use binary, but some *nix variants use SI.

freitasm

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#725000 30-Nov-2012 08:23

sbiddle:
hamish225:
the same thing happens with my terabyte hard drive, it's not a terabyte its 931gb. a TB is 1024GB not 931.

Incorrect.

A terabyte is 1000 gigabytes in using standard SI units or 931 gibibytes in binary.

Nope. While 1000 Gigabtyes is 1 Terabyte in SI units, the binary is always going to be 1 TB = 1024 GB, 1 GB = 1024 MB, 1 MB = 1024 KB, 1 KB = 1024 Bytes, 1 Byte = 8 bits.

This of course doesn't invalidate the previous answers about metric system being used for HDD storage marketing and filesystem space utilisation.

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sidefx

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#725003 30-Nov-2012 08:44

freitasm:
Nope. While 1000 Gigabtyes is 1 Terabyte in SI units, the binary is always going to be 1 TB = 1024 GB, 1 GB = 1024 MB, 1 MB = 1024 KB, 1 KB = 1024 Bytes, 1 Byte = 8 bits.

This of course doesn't invalidate the previous answers about metric system being used for HDD storage marketing and filesystem space utilisation.

Which is why everyone should use the binary prefixes to avoid confusion:

1TiB = 1024 GiB, 1 GiB = 1024 MiB, 1 MiB = 1024 KiB, etc

Not that that'll happen. Too much history in this. :)

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sbiddle

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#725029 30-Nov-2012 09:31

freitasm:
sbiddle:
hamish225:
the same thing happens with my terabyte hard drive, it's not a terabyte its 931gb. a TB is 1024GB not 931.

Incorrect.

A terabyte is 1000 gigabytes in using standard SI units or 931 gibibytes in binary.

Nope. While 1000 Gigabtyes is 1 Terabyte in SI units, the binary is always going to be 1 TB = 1024 GB, 1 GB = 1024 MB, 1 MB = 1024 KB, 1 KB = 1024 Bytes, 1 Byte = 8 bits.

This of course doesn't invalidate the previous answers about metric system being used for HDD storage marketing and filesystem space utilisation.

Sorry didn't make that clear. What I was meaning was that a 1000GB SI drive has 931 gibibytes of capacity which is the capacity you get when you format it with a typical file system.

sidefx

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#725052 30-Nov-2012 10:24

sbiddle:

Sorry didn't make that clear. What I was meaning was that a 1000GB SI drive has 931 gibibytes of capacity which is the capacity you get when you format it with a typical file system.

Which is correct and illustrates where the standardised binary prefixes are less confusing in distinguishing between the two:

1TB = 1000GB = 1 000 000 MB = 1000 000 000 KB = 1000 000 000 000 Bytes = 976 562 500 KiB = 953 674 MiB = 931 GiB

But given they've barely been adopted at all in the hardware\software industry the confusion is just something we live with.

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macuser

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#725053 30-Nov-2012 10:28

Mac OS now reports the Metric value of the drive to the user. So a 1TB drive looks like a 1TB drive in the OS. So I guess if you don't want to keep 'losing' HDD space, buy a Mac!

sidefx

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#725054 30-Nov-2012 10:29

macuser: Mac OS now reports the Metric value of the drive to the user. So a 1TB drive looks like a 1TB drive in the OS. So I guess if you don't want to keep 'losing' HDD space, buy a Mac!

Until you actually try and put 1TiB of files onto that drive? Or does it report file sizes in that way too? :)

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macuser

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#725058 30-Nov-2012 10:36

Yep it reports everything in Metric, so if you compared a file on a MacOS machine to a Win machine, you would find the file is slightly larger on the Mac.

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hamish225

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#725148 30-Nov-2012 13:54

oh that's interesting, i was always told it was because hard drive manufacturers were stingy.

What's stopping them from using the same system that Microsoft use?

also, why is there more than one system?

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freitasm

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#725153 30-Nov-2012 14:05

As suggested, read the Wikipedia articles.

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mattwnz

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#725161 30-Nov-2012 14:49

I would have thought that these days they would just make the drives slightly larger so when people connected them up, they would read as a round number and match that quoted on the packaging. It would at the least cut down on the number of people complaining about this. I get asked this question all the time still. I think they do usually have something printed on the box if you buy an external drive.

stevenz

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#725180 30-Nov-2012 15:15

Most drives will say how the measurement is derived on them, or at least, the last few WD units I've bought do.

1.44MB floppies wouldn't store 1.44MB either. This isn't a new "problem".

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