120GB on a 128GB Air?

Discussion in 'MacBook Air' started by altecXP, Nov 27, 2011.

  1. macrumors 65816

    Joined:
    Aug 3, 2009
    #1
    I know the Recovery drive takes up 650MB, but where is the other 7.25GB?
     
  2. macrumors 68030

    wrinkster22

    Joined:
    Jun 11, 2011
    Location:
    Toronto
    #2
    OS. read the box "Capaicity is formatted for less" An 8gb iPhone is actually only 6gb,
     
  3. thread starter macrumors 65816

    Joined:
    Aug 3, 2009
    #3
    Yes, but OS X Lion tends to show the full size. It does with my other SSD's and HDD's
     
  4. Mlrollin91, Nov 27, 2011
    Last edited: Nov 27, 2011

    macrumors 68020

    Mlrollin91

    Joined:
    Nov 20, 2008
    Location:
    Ventura
    #4
    128GB is really only 128,000,000,000 bytes instead of 137,000,000,000 bytes. So the actually drive is only roughly 124GB after conversion. Minus OS and Recovery drive bring it down to 120ish.

    Edit: After rechecking my math, 120GB is just over 128,000,000,000 bytes.
     
  5. thread starter macrumors 65816

    Joined:
    Aug 3, 2009
    #5
    Yes, but Lion, and I think SL, use 1000 not 1024
     
  6. macrumors G4

    Joined:
    Oct 23, 2010
    #6
    True, but SSDs are quoted based on their absolute size, which includes amounts that the controller sets aside for low level operations such as overprovisioning, wear leveling, and garbage collection (i.e. not available for data storage). The actual capacity of the 128GB SSD is about 121GB, while the 256GB capacity is actually about 250GB using the base 1000 system.
     
  7. macrumors 6502a

    johnhurley

    Joined:
    Aug 29, 2011
    #7
    Overhead and rounding off and formatting and SSD stuff ...
     
  8. macrumors 6502

    Joined:
    Jan 27, 2009
    Location:
    Montreal, Qc
    #8
    Must depend on the manufacturer, my intel 600GB show as 600 in sl/lion
     
  9. macrumors regular

    Joined:
    Jul 29, 2011
    #9
    The actual usable capacity of the 128 GB SSD in MBA is 113 GB.

    Apple is messing around a bit. They say 128 GB, but they don't count space taken for wear leveling etc.

    Coz for example Crucial M4 128 GB got actually over 119 GB of usable space.

    And Sandforce based drives already are sold as 120 GB not 128 GB, coz they really are a bit "smaller".
     
  10. thread starter macrumors 65816

    Joined:
    Aug 3, 2009
    #10
    Ah I didn't realize that they didn't count the wear leveling space. That totally makes sense now.
     
  11. macrumors 68020

    Mlrollin91

    Joined:
    Nov 20, 2008
    Location:
    Ventura
    #11
    That was my point. 1024 would be 137,000,000,000 bytes for 128GB. 128,000,000,000 would be 1000 for 128GB, but when you then use the formula, 128,000,000,000 bytes is truly 120ishGB.
     
  12. macrumors 6502a

    rbrian

    Joined:
    Jul 24, 2011
    Location:
    Aberdeen, Scotland
    #12
    I agree. After I installed Lion on my Pro, my hard drive capacity went from 931Gb to 1000Gb. At the same time, a 679Mb ISO wouldn't fit on a 700Mb CD, saying it needed 720Mb. Don't you just love standards? There are just so many to choose from! In practice though, you should keep about 10% of your storage capacity free, so it's all moot.
     

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