ACTUAL ipod hard drive size?

Discussion in 'Buying Tips, Advice and Discussion (archive)' started by CleverName01, Jul 23, 2004.

  1. CleverName01 macrumors newbie

    Jul 23, 2004
    I am going to buy either a 20GB or 40GB ipod in the next few weeks and I’m wondering what the ACTUAL size of the ipod 20GB hard drive is? I’m not the most savvy computer user and I don’t know the difference between “formatted” vs. “size” vs. “size on disk” (the last two are the sizes indicated when I right clickproperties on my music folder). Windows tells me the following:

    Size: 18.3 GB (19,705,150,881 bytes)
    Size on disk: 18.3 GB (19,709,083,648 bytes)

    What is the difference between these numbers!!? (stupid windows!) Is there 18.3GB OR 19.7GB of data/music?? Can this fit on a 20GB ipod? If I needed to delete data/music to fit on the 20GB ipod, how much would I have to delete? What is the formatted size of the 20GB hard drive? As you can tell, I have my heart set on a 20GB (mostly because of price).

    Hopefully, someone with more knowledge of computers than me can answer these questions and give me some advice. Thanks in advance
  2. superbovine macrumors 68030


    Nov 7, 2003
    here is the math
    8 bit = 1 byte
    1 kb = 1024 byte
    1 gb = 1024*1024*1024

    19,709,083,648/(1024*1024*1024) = 18.35551452636719 GB

    18.3 GB
  3. Horrortaxi macrumors 68020


    Jul 6, 2003
    Los Angeles
    18.3ish sounds about right for formatted capacity on a 20GB drive. I doubt you'll get as high as 19.
  4. EminenceGrise macrumors member

    Jun 23, 2004
    It was like BLEEP BLEEP BLEEP....

    ...and then my post was gone. And I was like "Nggg?" It was a really good post too, and now I have to re-write it fast, and it won't be as good. It's kind of like.... a bummer.


    Size == Size of the actual data in the files.
    Size on Disk == Size of the files as allocated on disk.

    The difference comes about because of the way space on a hard drive is allocated for storage. When you format a drive, it builds the filesystem which uses discreet chunks (called blocks) on the disk to store files. One file, and only one file, can have data stored in any given block. Now, if the data in a file isn't an exact multiple of the size of the filesystem blocks, it wastes some of the space in the last block used by the file, because the space can't be used by any other file. So, for example if we have a filesystem which uses 4KB blocks, and four files 1KB,2KB,3KB and 4KB in size, each one of those files use up 4KB on disk, since that is the smallest amount of space that can be used for a file. Likewise, if we had a 5KB file, it would take up 8KB on disk (one 4KB block with 4KB of data in it and one 4KB block with 1KB of data, with 3KB "wasted"). "Size on Disk" is accounting for the lost space due to how the filesystem compartmentallizes data - in your case, about 3.75MB total are unused, but can't be allocated for other files. Macs do the same thing, BTW - this is one case where Windows is actually doing something right....

    Now, the real problem comes when you get to the hard drive size. Hard drive manufacturers, in their infinite wisdom, have decided to define 1GB = 1,000,000,000 bytes, while everyone else in the computer industry uses the "base 2" GB which is 1,073,741,824 bytes - this is because computers use binary, so using powers of 2 is natural. Note that 1000 is not a multiple of 2, but 1024 is, so it was used for the "computer definition" of the Kilo, Mega, and Giga prefixes (I will leave out the diatribe about the folly of misappropriating an accepted standard (SI) in such a fashion). The downside to this, is that a "20GB" hard drive is only 18.63GB as far as your computer and OS are concerned, and that is before formatting, which will take up more space (perhaps leaving you with around 18.0GB that is actually usable, depending on filesystem and block allocation). The hard drive manufacturers originally used the "standard" computer convention, until they realized they could instantly increase the size of their hard drives simply by changing the definition to the SI standard. Welcome to the joy of capitalism.

    So, to answer your question, a 20GB iPod will probably not hold your entire music collection. I would say as an extreme upper limit, you would have to sacrifice 1GB somewhere, although it would probably be closer to 500MB or perhaps less. Don't forget some of the space on the iPod is used for the iPod's software (but probably only 20MB at the most). If you could live without some of your music at any given time, the 20GB iPod would probably be fine, but you would have to manually manage the files and playlists to make space (you could keep all of your files on the PC that way, and just the ones you wanted on the iPod). If you want to have all your music on the iPod all of the time, and more important room to grow, get the 40GB iPod.
  5. klaus macrumors 6502a


    Feb 4, 2004
    So, in that case, it's normal that my mini says 3.7 gb available when purchased. And not the 'expected' 4 gb?
  6. Horrortaxi macrumors 68020


    Jul 6, 2003
    Los Angeles

Share This Page