External HDs show up as larger than possible - Help

Discussion in 'Mac Accessories' started by LoveHopeHero, Mar 30, 2010.

  1. LoveHopeHero macrumors newbie


    Feb 16, 2010

    I bought my second WD Elements 1.5 TB External HD last night and I cleaned out my old 250 GB LaCie External HD today. I know the 1.5 TB should read at about 1.4 TB and the 250 GB has always read at about 232 GB. Suddenly I have them at 1.5 TB and 249.4 GB respectively.

    Sounds like things the way they should be, I know, but anyone who's been paying attention knows something's just not right there. Anyone know what happened? And if it's not a glitch tell me how to reproduce the result on my other HDs.

    Thanks in advance.
  2. Darth.Titan macrumors 68030


    Oct 31, 2007
    Austin, TX
    If you're using Snow Leopard then nothing at all is wrong. Snow Leopard gives drive sizes in base 10 instead of base 2, so a 1.5 TB drive should show up as 1.5 TB.

    I notice that your sig says you're on an i& iMac, so you're definitely on Snow Leopard.
  3. LoveHopeHero thread starter macrumors newbie


    Feb 16, 2010

    So what if my older external was set up using just Leopard, would the drive need reformatting to take advantage of the extra space? Sorry this is all news to me. Good news though.
  4. LoveHopeHero thread starter macrumors newbie


    Feb 16, 2010

    I just had to inspect a bit. Thank you. Good news all around here.
  5. waw74 macrumors 68030

    May 27, 2008
    there is no extra space, it's just the way that it's being counted. Apple has just switched to the same counting method as the manufacuters. so the 1.5 on the box the drive comes in will equal 1.5 on the screen of your computer.

    manufacturers (and snow leopard now) use base 10 math. so
    1 Megabyte = 1000 Bytes

    compters use base 2 math (binary) so
    1 Megabyte (technically Mebibyte) = 1024 Bytes

    once you get up there, the differnce is substantial
    1 Gigabyte = 1,000,000,000 Bytes
    1 Gibibyte = 1,073,741,824 Bytes

    so per GB, it 73 megabytes difference in the numbers.

Share This Page