Coding Horror: “If you’re wondering where 35 Gigabytes of your 500 Gigabyte drive just disappeared to, you’re not alone. It’s an old trick perpetuated by hard drive makers– they intentionally use the official SI definitions of the Giga prefix so they can inflate the the sizes of their hard drives, at least on paper. This was always an annoyance, but now it’s much more difficult to ignore, as it results in large discrepancies with today’s enormous hard drives. When is a Terabyte hard drive not a Terabyte? When it’s 931 GB.”