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Q: Reformat Bootable OSx USB Installer

After creating a bootable OSx installer to reinstall my OS, the USB drive I used won't reformat correctly. Regardless of the file format chosen, the 64GB drive is shown to have a capacity of only 8GB. I've tried every variation of formatting available in disk utility as well as one free third party disk utility, and I got nothing.

 

Is there a sudo command that I can use to format the drive properly?

MacBook Pro (Retina, 13-inch, Early 2013), OS X El Capitan (10.11.4), Samsung USB 3.0 64GB Drive

Posted on May 23, 2016 4:09 AM

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Q: Reformat Bootable OSx USB Installer

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  • by JimmyCMPIT,

    JimmyCMPIT JimmyCMPIT May 23, 2016 4:41 AM in response to astrowerx
    Level 5 (7,035 points)
    Mac OS X
    May 23, 2016 4:41 AM in response to astrowerx

    the terminal command to format a volume is:

    sudo diskutil reformat <volumename>

    use at your own risk and remember there is no undo for any problems caused by this the computers doing what it's told instead of what you wanted.

     

    BEFORE resorting to that I would

    check to see if the drive is partitoned

    check to see if the drive is locked

    try reformatting on a Windows PC if one is available then taking back to the mac

    and

    Always have an up-to-date backup of ALL your data.

  • by Barney-15E,

    Barney-15E Barney-15E May 23, 2016 4:49 AM in response to astrowerx
    Level 8 (49,772 points)
    Mac OS X
    May 23, 2016 4:49 AM in response to astrowerx

    You don't need sudo to format a drive.

    You can try using diskutil in the Terminal.

    You'll first need to diskutil list to see what the drive identifier is, like disk6

    Then,

    diskutil partitionDisk disk6 GPT jhfs+ Untitled 100%

     

    However, if it is a CoreStorage volume, then you'll have remove the CoreStorage format, first.

    If it is CoreStorage, you'll see a blurb starting with "Logical Volume" below the NAME column.

  • by keg55,

    keg55 keg55 May 23, 2016 5:58 AM in response to astrowerx
    Level 6 (8,368 points)
    Mac OS X
    May 23, 2016 5:58 AM in response to astrowerx

    Instead of formatting, select the actual drive in Disk Utility (top most line, not indented) and do an erase or click the Partition tab. This will create a single partition with the format you choose.