[X4U] External HD: 750 gig to 699 when formatted. Why???

[Chris Jones]

Germain M. wrote:
> Hello,
> I bought a SimpleTech 750gig external HD. It was Windows formatted in 
> the first place. Once mounted, info window showed the drive had 699 gig 
> free. As suggested in the instruction manual (and as should be done) 
> anyway), I reformated the drive Mac OS Extended journaled. Still 699 gig 
> free. Is there a way te recover this huge amount of lost gig? What are 
> they used for and by what (whom)? Are there some hidden Windows programs 
> and files left on the HD. If so, how to et rid of them to recover that 
> space?

Don't worry, this is a trick used by disk makers to make their disks 
seem larger than they are. Basically, they use a difference definition 
of 'GB' to what your system is using.

They use a system where '1 gigabyte' = 1000000000 bytes, whereas your 
system uses '1 gigabyte' = 1073741824.

If you want more details, see for instance

http://en.wikipedia.org/wiki/Gigabyte

The confusion comes from the fact the term 'GB' tends to used for both 
definitions. The correct thing to do is to use 'GiB' for the system used 
by the hard disk makers. So your disk is actually 750 GiB or in other 
units, 699 GB. If you do the maths you will see 
(1073741824/1000000000)*699 = 750

So don't worry. You haven't lost any disk space, its just not quite as 
big as you thought...

Chris