Thread: Where's the Space?

I have always enjoyed reviews of PC hardware in every issue of your mag. Recently, I purchased a Seagate 500GB sata hard disk, but I was disappointed that on installation and after format¬ting, it showed only 465GB of usable space; that's almost 35GB (around 7 DVDs @J 4.5GB/(5x) times space used by Vista after installation) of space gone! I can understand 5 or 10GB going for system files and such, prior to OS installation; but 35? Kind of defeats the purpose of being cost effective doesn't it? I checked on the Web and found that it was normal for that size hard disk. Lower capacities like 250 320GB would have lost much less, so it would have been more cost effective overall purchasing two of those, besides the advantages of setting them up in a RAID config.

I feel so cheated!

Editor's Reply: Yes, anyone who's bought a hard drive has noticed this. The reason for the discrepancy is the way manufacturers measure a megabyte. Manufacturers treat a kilobyte as 1,000 bytes, a megabyte as 1,000 kilobytes, a gigabyte as 1,000 megabytes, and a terabyte as 1,000 gigabytes. This is accurate according to the SI system (1,600 gms in a kg, right). In computers though, the prefixes of kilo, mega, giga and tera, refer to powers of two, n?t ten. Standards organizations have tried to get people to call them kibi, mebi, and so on, but that hasn't really worked. So a real kilobyte, as used by every desktop computer operating system, contains two to the power of ten, 2"10, 1024, bytes. A real megabyte contains 2"20, 1,048,576, bytes. A real gigabyte contains 2"30, 1,073,741,824, bytes. A real terabyte contains 2"40, 1,099,511,627,776, bytes.

The difference between the powers of ten and the power of two gets worse and worse as capacities increase. There really is no solution for this, unless manufacturers voluntarily start labeling drives in powers of two. We have considered mentioning the actual capacity of the drive in our reviews, but that can cause readers to get confused about why the capacity is less than what's written on the drive. We would have to attach an explanatory note to every review to avoid this. Also, since each and every manufacturer does this, it's not really a differentiating factor. We do, however, bring this fact up every so often in columns like Fact Check so that our readers are aware of this issue. And we've felt cheated too, so we share your irritation.