Brain Drippings

We’ve all seen it, and some of us pobably even believe it. There we are, minding our own business and there it is, someone starts waxing poetic about ‘formatted’ versus ‘unformatted’ Hard Drive storage. You may even hear some salf-assigned pundit say something like, “Well, of course once you format a 200GB drive you’ll find the formatted capacity is a bit less.”

Codswallop!

The reason that a 200GB drive does not format to 200GB has nothing to do with ‘formatting’ it has to do with Hard Drive manufacturers lying about capacities.

Apple used to hold the line and sold machines with “100MB” drives that actually held 100MB while other sold the IDENTICAL drive as “104MB”.

Here’s the math:

• 1GB = 1,073,741,824 bytes
• 200GB = 214,748,364,800 bytes

However, Hard Drive vendors sell a drive that hold 200,000,000,000 bytes as a “200GB” drive. Simple math will show you that a drive that holds 200,000,000,000 bytes is, in fact, 186.25GB drive and not a 200GB drive. And when you format a “200GB” drive you get a drive that holds, amazingly enough, 186.25GB¹. You didn’t lose 14GB, it was never there.

A good way to remember this lie is the so-called “137GB barrier”. You may have wondered at this odd number. It is especially odd in having anything to do with computer storage since 137 is no where near a multiple of 2. That’s because the old ATA barrier was 128GB (go on, do the math). Nothing to do with “formatted capacity” or “unformatted capacity”.

¹OK, probably not. It is more likely to be slightly more. For example, my 160GB drive holds 152GB instead of the 149.01 it should.