6 Replies Latest reply: Sep 6, 2010 4:22 AM by thomas_r.
cliko Level 1 Level 1 (0 points)
Okay, I got a new 4GB USB memory stick and tried to encrypt it with this program. Anyway, it didn't work so I reformatted it with Disk utility. However, I noticed the size had changed. It said "4.01 GB Lexar USB Flash Drive Media" and underneath it had what I had named my USB. I clicked on the latter and its size was only 3.8 GB. I tried deleting the partition and making a new one with the size being specifically 4.01 GB, but now it's only 3.67 GB. What can I do?

iMac and MacBook Pro, Mac OS X (10.6.4)
  • noondaywitch Level 6 Level 6 (8,130 points)
    Nothing; that's perfectly normal as the partiton and format leaves file structure settings, .Trash and other files required for OS X to read and write to the stick, which take up some of the memory space.
  • daba_nz Level 1 Level 1 (15 points)
    Reformat it.

    1. Click on the parent drive (4.01 GB CHIPBNK ...)
    2. go to the "erase" tab
    3. Select either:
    - "MS DOS" for Mac & PC
    - "Mac OS extended (Journaled)" for the faster Mac only option
    4. Give it a name
    5. Click erase

    If you want to attach extra security, you could create a separate "disk image" by going to "File > New > Blank Disk Image", making it slightly under 4GB (trail & error) and adding security options. Save that image to your USB.

    As for the size of the drive:
    The size will always be the same, but the usable data may change depending on formatting, security and partition map settings.
    Another thing is that there is a difference between gigabits and gigabytes; goes up in 10s (100, 500, 1000) while the other goes up in exponents (256, 512, 1024, 2048). This causes misconception. USB producers will tell you that 1000 = 1GB while MAC OSX will tell you that 1024 = 1GB; this allows producers to make it seem that you are paying more data.
    I'm sure someone can explain this better...
  • cliko Level 1 Level 1 (0 points)
    i completely understand you daba_nz, but i didn't think there would be 200 MB in difference.... disk utility says that the flash drive is 4 GB, but that the actual thing on the desktop is 3.8 GB, it's hard to explain. Here is a acreenshot


    See, the actual thing is 4.01 GB but 'USB STICK' is only 3.8 GB.
  • noondaywitch Level 6 Level 6 (8,130 points)
    To illustrate my point about the files used for formatting etc., go to Disk Utility, highlight the HD (leftmost one with the disk info) and read the size at the bottom right. Then highlight Macintosh HD (which is the partition) and read the size of that.

    The difference will almost certainly be somewhere around 350 to 400 MB. As the same formatting etc files are used for any drive, the difference you show is perfectly normal.
  • cliko Level 1 Level 1 (0 points)
    Your right noonday, there is about 450 MB difference with my Macintosh HD between what its supposed to hold and what it can. Thanks guys for all your help!
  • thomas_r. Level 7 Level 7 (30,545 points)
    There are all manner of disk structures required to keep track of files and folders, and those structures take up part of the drive's space.