1500gb hard drive is only 1360gb...is that acceptable?

[joko]

ive just bought a hard drive advertised as 1500gb ...however on plugging it in it is only 1360gb ... 14gb less...

is that normal for a drive of that size...?

now i know that most drives are just under the amount they claim to be and have yet to see one that registers exactly...but 14gb under seems rather a lot...

there is no software - its just plug and play - so why so much?

cheers

[jno]

140gb in fact...

[rojash]

It's about right, dues to the difference in the way that Hard disk manufacturers calculate the size of a Gigabyte compared with the way normal people calculate it.

i.e: Real Gigabyte = 1 073 741 824 bytes
Hard disk manufacturer's Gigabyte = 1 000 000 000 bytes

It's a good thing that (say) Petrol companies don't have their own method of calculating a litre :-)

[rojash]

... should have pointed out (though it's pretty obvious) that the bigger the hard drive, the bigger the discrepancy.

[VHG]

The problem is how the hard disk makers measure a gigabyte. Hard disk makers tend to "round up" the figure to make them simpler (and make the hard disk seem bigger).

For techincal reasons computers use a measurement of 1024 (so a kilobyte is 1024 bytes, a megabyte is 1024 kilobytes, and a gigabyte is 1024 megabytes). This makes a gigabyte 1,073,741,824 bytes.

But a hard disk makers will call a gigabyte 1,000,000,000 bytes to make it simpler.

So if you compare the "real" 1,073,741,824 bytes to the 1,000,000,000 bytes that the HDD manufacturers use, you can see that there is over a 7% difference! Therefore Windows will report the hard disk as being approximately 7% smaller than the hard drive manufacturer's quoted size.

[Buenchico]

'Kilo' means 10 to the power of 3. (i.e. 1000). However computers use binary arithmetic. Those who work in the field quickly decided that it would make more sense to interpret 'kilo' as meaning 2 to the power 10 (=1024), rather than as 1000. Following on from that, 'Mega' came to be interpreted as 2 to the power of 20 (= 1,048,576), rather than as 1,000,000, for computer purposes. As the numbers used by computer designers got bigger, it then followed on that 'Giga' came to mean 2 to the power of 30 (= 1,073,741,824), rather than as 1 billion.

So a hard drive which has 1500 billion (real) bytes will have {1500 divided by 1.073741824} (computer) Gigabytes, which is about 1397 (computer) GB. That would partially account for the apparent deficit which you've reported. However I suspect that the '1500' in the description might actually refer to 1.5 x 2^10, rather than 1.5 x 10^3. In which case, a factor of 1.024 needs to be brought into the calculation, giving a disk size of roughly1364 (computer) GB. That would certainly be the case if the drive was actually described as '1.5 Terrabytes'.

It has always been the convention that hard drive manufacturers will report the true number of bytes available on their products, even though the computers that those drives are placed in will then report a lower figure (because the computer requires 1024 bytes to make up one Kilobyte, rather than 1000). As drive sizes get bigger, the differences become more marked.

Chris

[jno]

you joined AB just to post one word, bisquit?

[AlBags]

^ ^ No Google

[joko]

oh yes 140gb...sounds even worse now!

thanks all - i wondered if they'd actually sent me the wrong one...

still sounds an awful lot though - thats more than my laptop one!

it was listed as 1.5TB and 1500gb

[beso]

The use of kilo to represent 2^10 (and the associated Mega and Giga multipliers) was an ad hoc implementation.

By definition Kilo means one thousand, Mega is one million and Giga is a billion. These are standards defined by the SI authority. Unfortunately their use in the binary context became widespread before the SI authority became aware of the misuse.

The use of the binary variant was never approved. Consequently their use in the binary form is incorrect and the usage by disk drive manufacturers is wholly legitimate.

The terms kibi, mibi and gibi have been approved by SI for the binary based multipliers but have not been adopted by the industry.

However, strictly speaking, when a disk drive is referred to as 140 GB it means 140 Gigabytes while 1 GB of RAM is one Gibibyte

[beso]

BTW. While Microsoft measures file sizes in Kibibytes, Mac and Linux systems use Kilobytes.