MBA- Formatted Storage - Help Needed

Discussion in 'MacBook Air' started by kommineni, Dec 16, 2010.

  1. kommineni macrumors newbie

    Dec 16, 2010

    Long time lurker - First time poster

    I was just going through my storage usage and I just found that the formatted storage on my Air (1.86-128-4) is 112 GB (62 for OSX + 50 for Bootcamp), I noticed this when I was doing my bootcamp partition but ignored it. So, out of the 128GB, do we have only 112 GB to play with?

    Curiously, I've not seen anyone having to deal with just 112 Gigs (unless I'm missing some thing)

  2. bamf macrumors 6502

    Feb 14, 2008
    My 13" MBA shows 121.33GB available in Disk Utility. The remainder is used by the SSD as spare area. The drive does have 128GB of flash on it, but the usable area is misleading at best.

    Now, you say you have 112GB. Can you go into disk finder and tell me what the disk says please because 112GB does not make sense.

    Also, are you reporting your space "normally" or in Base 10?
  3. kommineni thread starter macrumors newbie

    Dec 16, 2010
    Well, disk utility shows 121.33 but when I use something like Disk Inventory X, it shows that my Mac HD capacity is 52 GB while Bootcamp is 60 GB - which I believe is the 'normal' space (Sorry, I mistyped in my last post, I actually gave 60 gb to windows when I partitioned the HD)

    And if I remember right, when I did my bootcamp partition, I had only 112 GB total to play with and not 121.3
  4. bamf macrumors 6502

    Feb 14, 2008
    That's the difference between using 1024 bits per kilobyte and Base 10. I think your machine is just fine.
  5. Thiol macrumors 6502a


    Jan 26, 2008
    Yeah, this is sort of annoying. All the SSDs I've ever used actually advertise the usable area. Apparently, some others, like Apple, advertise the total area prior to accounting for overprovisioning. I wish they'd all pick one standard...
  6. Anonymous Freak macrumors 603

    Anonymous Freak

    Dec 12, 2002
    Companies also use disk space in base-10.

    So "128 GB" is 128,000,000,000 bytes.

    Most OSes use base-2.

    So "128 GB" is 128*2^30, or 137,438,953,472 bytes.

    If you turn the base-10 number into base-2, you get.... 119.2 GB in base-2. (Some people try to use a new prefix "Gibi", abbreviated "Gi" to define a base-2 2^30, so would write that as 119.2 GiB. I can't stand this rebranding, but it's what some people use to differentiate.)

    So that "128 GB" would show up as "119.2 GB" at "full" capacity. A little bit of that is lost in formatting and spare space.
  7. Thiol macrumors 6502a


    Jan 26, 2008
    We've discussed this in other threads. The Apple "128 GB" disk yields 120.99 GB (in base-10, not base 2). That's more than the expected base-2 119.2 GB if the Apple "128 GB" was base-10. In fact, the OP and the rest of us only see base-2 112.7 GB. The difference (Apple's 128 GB vs. what we all see) is due to SSD overprovisioning and not the base conversion.
  8. kommineni thread starter macrumors newbie

    Dec 16, 2010


    I also think Apple is inconsistent in this regard. I gave the Bootcamp partition 60 GB (atleast that's what bootcamp assistant showed) when I did the partition but right after the partition and the install, the partition was and countinues to be listed at 65GB capacity.
  9. KPOM macrumors G5

    Oct 23, 2010
    Boot Camp Assistant still uses the base 1024 standard. It's confusing, to be sure, as is Apple's use of the raw capacity of the SSD rather than its net capacity (after overprovisioning).

    With SSDs, I think manufacturers ought to say both numbers. Knowing whether a drive is overprovisioned is important information. I purchased a Crucial SSD as a backup drive. It is 128GB and has no overprovisioning, so I get the whole 128GB, but miss out on the benefits of overprovisioning (indeed, some of Digilloyd's tests on Crucial drives show significant performance degradation over time). Since I'll copy to it once or twice a month I don't care so much, but it would make a difference if I were planning to make it a primary drive.

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