Question about HD size

[mara-]

Hi,

Recently I bought new HD, WD WD5000AAKS. It's capacity is 500GB, but when I open properties in my computer it shows 465GB. What happened with 35GB? I noticed this generally with HD's. My other HD which has 200GB capacity, actually has 186GB. Can somebody explain me why HD does not have capacity as manufacturer claims?

Cheers

[CoffeeFiend]

Hard drives have been sold like this for a very long time. They sell their hard drives as 1 gigabyte = 1000000000 bytes, whereas you were expecting 1073741824 bytes in a GB.

So your hard drive is 500 * (1000000000/1073741824) GB, or roughly 465GB.

Here's a quick list of "advertized" drive capacities, versus "real" GBs (no decimals):

20 GB: 18 GB

40 GB: 37 GB

80 GB: 74 GB

160 GB: 149 GB

200 GB: 186 GB

250 GB: 232 GB

320 GB: 298 GB

500 GB: 465 GB

640 GB: 596 GB

750 GB: 698 GB

1000 GB: 931 GB

Edited August 24, 2008 by crahak

[Zxian]

It's actually a misnomer in computer terms.

Kilo (10^3), Mega (10^6), Giga (10^9), Tera (10^12) - these all describe powers of 10.

Kibi (2^10), Mebi (2^20), Gibi (2^30), Tebi (2^40) - these all describe powers of 2.

These terms are often mixed up. In any piece of software, things are measured in the powers of 2 (computers are binary systems afterall). In hard drive manufacturing, they use the powers of 10. crahak already gave the conversion factors above, but this is the reason behind it all.

[CoffeeFiend]

Well, that's the "new names" some people use to differentiate. But seriously, go in a computer shop, and ask them for a 500 gibibyte hard drive, or talk with a co-worker about kibibytes, and you're gonna get some weird looks. Similarly, some hardware sold goes by powers of 2 too like RAM (when you get 2GB of RAM, it's 2048MB, not 2000MB). In practice, nobody actually uses those fancy terms, even though we're really misusing SI prefixes... I just tried to explain it the easy way, without involving weird words

You're still completely right

[mara-]

OK, thanks for answers guys. I understand now.

Cheers

[Ponch]

to sum it up,

500.000.000.000 bytes is what you buy,

465,7 x 1024 x1024 x1024 bytes is what Windows reports as GigaBytes, cause 1Kilobyte is 1024 bytes (10^2), etc.

Which is the same if you do the math.

[GrofLuigi]

It reminds me of an old joke about two programmers:

- how's your new job?

- fine, fine...

- how's the boss treating you?

- fine, fine...

- what does he pay you?

- 1000 $

- that bastard! Couldn't he round it up to nice even number like 1024 ?!

GL

Edited August 25, 2008 by GrofLuigi