Why is it when you buy a Hard Drive you always get less Gigs than what you pay for?

Richard J. Johnson

Richard J. Johnson

Joystick Member
I'm sure this has been posted before but I could not an answer. If I buy a 500 gig drive There are always less gigs on the drive. anyone know why. Every Lacie FW drive I own and I own a lot, comes with less space then they list on the packaging.
 
They define 'gigabyte' differently. In the computer it's 1,073,741,824 bytes. The manufacturers say it's 1,000,000,000 bytes, mostly in order to have a bigger sounding device with less stuff in it. Now it's a standard not likely to change.
 
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There are two reasons. Firstly, there are 1024 bytes in a kilobyte, 1024 kilobytes in a megabyte, 1024 megabytes in a gigabyte and so on. Manufacturers conveniently assume that there are 1000 for each. For a 100 GB drive, this means that you're getting a 93.13 GB drive in actual terms. 7% error! (100 000 000 000 / 1023^3) It could be slightly different depending on the manufacturer, some might not switch from 1024 to 1000 until MB or GB.
The second reason is that the disk must be formatted so that the computer knows how large it is, what kind of filesystem it's using e.t.c. and that also takes up space.
 
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A better question would be, "Why, when you buy all this production gear do you get less gigs then you paid for?"


A. The inverse friend law states that the more production friends you have the less pay you get per gig until you draw the line in the sand with a dollar sign like this $_____ and invariably the number under that will become 0.
 
filthrich said:
Thanks for the info. Why can't they just make an adjustment and give the consumer what they pay for?
Click to expand...

Welcome to the wonderful world of marketing.... This is a very common case of "puffing" the numbers higher than what they really are. Say you buy a 2,000 square foot house; if you measure each room and add the results, there's a lot less than 2,000 square feet. It seems that the real estate agents measure the outside of the house, which includes all the space in the walls. So in the end, you have less than 2,000 of usable square feet.

It's already been pointed out that hard drives have to use some of the space for tables and other pointers to keep track of files. It's a bit like the walls in our house. This partition information is there in the drive, BUT you can't use it as usable file storage space.

Some may remember the 17" monitors that had only 15 - 15.5" of image on them. It turned out the 17" was the outer diagonal of the tube.

Then again, a 1/3" image sensor isn't really 1/3" of active pixels. It's a bit less than that.

Bob Diaz
 
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